TH3.cxx

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// @(#)root/hist:$Id$
// Author: Rene Brun   27/10/95
 
/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#include "TROOT.h"
#include "TBuffer.h"
#include "TClass.h"
#include "THashList.h"
#include "TH3.h"
#include "TProfile2D.h"
#include "TH2.h"
#include "TF3.h"
#include "TVirtualPad.h"
#include "TVirtualHistPainter.h"
#include "THLimitsFinder.h"
#include "TRandom.h"
#include "TError.h"
#include "TMath.h"
#include "TObjString.h"
 
#include <algorithm>
#include <atomic>
#include <stdexcept>
 
 
/** \addtogroup Histograms
@{
\class TH3C
\brief 3-D histogram with a byte per channel (see TH1 documentation)
\class TH3S
\brief 3-D histogram with a short per channel (see TH1 documentation)
\class TH3I
\brief 3-D histogram with an int per channel (see TH1 documentation)
\class TH3L
\brief 3-D histogram with a long64 per channel (see TH1 documentation)
\class TH3F
\brief 3-D histogram with a float per channel (see TH1 documentation)
\class TH3D
\brief 3-D histogram with a double per channel (see TH1 documentation)
@}
*/
 
/** \class TH3
    \ingroup Histograms
The 3-D histogram classes derived from the 1-D histogram classes.
All operations are supported (fill, fit).
Drawing is currently restricted to one single option.
A cloud of points is drawn. The number of points is proportional to
cell content.
 
- TH3C a 3-D histogram with one byte per cell (char). Maximum bin content = 127
- TH3S a 3-D histogram with two bytes per cell (short integer). Maximum bin content = 32767
- TH3I a 3-D histogram with four bytes per cell (32 bit integer). Maximum bin content = INT_MAX (\ref intmax3 "*")
- TH3L a 3-D histogram with eight bytes per cell (64 bit integer). Maximum bin content = LLONG_MAX (\ref llongmax3 "**")
- TH3F a 3-D histogram with four bytes per cell (float). Maximum precision 7 digits, maximum integer bin content = +/-16777216 (\ref floatmax3 "***")
- TH3D a 3-D histogram with eight bytes per cell (double). Maximum precision 14 digits, maximum integer bin content = +/-9007199254740992 (\ref doublemax3 "****")
 
<sup>
\anchor intmax3 (*) INT_MAX = 2147483647 is the [maximum value for a variable of type int.](https://docs.microsoft.com/en-us/cpp/c-language/cpp-integer-limits)<br>
\anchor llongmax3 (**) LLONG_MAX = 9223372036854775807 is the [maximum value for a variable of type long64.](https://docs.microsoft.com/en-us/cpp/c-language/cpp-integer-limits)<br>
\anchor floatmax3 (***) 2^24 = 16777216 is the [maximum integer that can be properly represented by a float32 with 23-bit mantissa.](https://stackoverflow.com/a/3793950/7471760)<br>
\anchor doublemax3 (****) 2^53 = 9007199254740992 is the [maximum integer that can be properly represented by a double64 with 52-bit mantissa.](https://stackoverflow.com/a/3793950/7471760)
</sup>
*/
 
 
////////////////////////////////////////////////////////////////////////////////
/// Default constructor.
 
TH3::TH3()
{
   fDimension   = 3;
   fTsumwy      = fTsumwy2 = fTsumwxy = 0;
   fTsumwz      = fTsumwz2 = fTsumwxz = fTsumwyz = 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for fix bin size 3-D histograms.
/// Creates the main histogram structure.
///
/// \param[in] name name of histogram (avoid blanks)
/// \param[in] title histogram title.
///            If title is of the form `stringt;stringx;stringy;stringz`,
///            the histogram title is set to `stringt`,
///            the x axis title to `stringx`, the y axis title to `stringy`, etc.
/// \param[in] nbinsx number of bins along the X axis
/// \param[in] xlow low edge of the X axis first bin
/// \param[in] xup upper edge of the X axis last bin (not included in last bin)
/// \param[in] nbinsy number of bins along the Y axis
/// \param[in] ylow low edge of the Y axis first bin
/// \param[in] yup upper edge of the Y axis last bin (not included in last bin)
/// \param[in] nbinsz number of bins along the Z axis
/// \param[in] zlow low edge of the Z axis first bin
/// \param[in] zup upper edge of the Z axis last bin (not included in last bin)
/// \note if xup <= xlow/yup <= ylow/zup <= zlow, automatic bins are calculated when buffer size is reached
 
TH3::TH3(const char *name,const char *title,Int_t nbinsx,Double_t xlow,Double_t xup
                                     ,Int_t nbinsy,Double_t ylow,Double_t yup
                                     ,Int_t nbinsz,Double_t zlow,Double_t zup)
     :TH1(name,title,nbinsx,xlow,xup)
{
   fDimension   = 3;
   if (nbinsy <= 0) {
      Warning("TH3","nbinsy is <=0 - set to nbinsy = 1");
      nbinsy = 1;
   }
   if (nbinsz <= 0) {
      Warning("TH3","nbinsz is <=0 - set to nbinsz = 1");
      nbinsz = 1;
   }
   fYaxis.Set(nbinsy,ylow,yup);
   fZaxis.Set(nbinsz,zlow,zup);
   fNcells      = (nbinsx+2)*(nbinsy+2)*(nbinsz+2);
   fTsumwy      = fTsumwy2 = fTsumwxy = 0;
   fTsumwz      = fTsumwz2 = fTsumwxz = fTsumwyz = 0;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size (along X, Y and Z axis) 3-D histograms using input
/// arrays of type float.
///
/// \param[in] name name of histogram (avoid blanks)
/// \param[in] title histogram title.
///        If title is of the form `stringt;stringx;stringy;stringz`
///        the histogram title is set to `stringt`,
///        the x axis title to `stringx`, the y axis title to `stringy`, etc.
/// \param[in] nbinsx number of bins
/// \param[in] xbins array of low-edges for each bin.
///            This is an array of type float and size nbinsx+1
/// \param[in] nbinsy number of bins
/// \param[in] ybins array of low-edges for each bin.
///            This is an array of type float and size nbinsy+1
/// \param[in] nbinsz number of bins
/// \param[in] zbins array of low-edges for each bin.
///            This is an array of type float and size nbinsz+1
 
TH3::TH3(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins
                                           ,Int_t nbinsy,const Float_t *ybins
                                           ,Int_t nbinsz,const Float_t *zbins)
     :TH1(name,title,nbinsx,xbins)
{
   fDimension   = 3;
   if (nbinsy <= 0) {Warning("TH3","nbinsy is <=0 - set to nbinsy = 1"); nbinsy = 1; }
   if (nbinsz <= 0) nbinsz = 1;
   if (ybins) fYaxis.Set(nbinsy,ybins);
   else       fYaxis.Set(nbinsy,0,1);
   if (zbins) fZaxis.Set(nbinsz,zbins);
   else       fZaxis.Set(nbinsz,0,1);
   fNcells      = (nbinsx+2)*(nbinsy+2)*(nbinsz+2);
   fTsumwy      = fTsumwy2 = fTsumwxy = 0;
   fTsumwz      = fTsumwz2 = fTsumwxz = fTsumwyz = 0;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size (along X, Y and Z axis) 3-D histograms using input
/// arrays of type double.
///
/// \param[in] name name of histogram (avoid blanks)
/// \param[in] title histogram title.
///        If title is of the form `stringt;stringx;stringy;stringz`
///        the histogram title is set to `stringt`,
///        the x axis title to `stringx`, the y axis title to `stringy`, etc.
/// \param[in] nbinsx number of bins
/// \param[in] xbins array of low-edges for each bin.
///            This is an array of type double and size nbinsx+1
/// \param[in] nbinsy number of bins
/// \param[in] ybins array of low-edges for each bin.
///            This is an array of type double and size nbinsy+1
/// \param[in] nbinsz number of bins
/// \param[in] zbins array of low-edges for each bin.
///            This is an array of type double and size nbinsz+1
 
TH3::TH3(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins
                                           ,Int_t nbinsy,const Double_t *ybins
                                           ,Int_t nbinsz,const Double_t *zbins)
     :TH1(name,title,nbinsx,xbins)
{
   fDimension   = 3;
   if (nbinsy <= 0) {Warning("TH3","nbinsy is <=0 - set to nbinsy = 1"); nbinsy = 1; }
   if (nbinsz <= 0) nbinsz = 1;
   if (ybins) fYaxis.Set(nbinsy,ybins);
   else       fYaxis.Set(nbinsy,0,1);
   if (zbins) fZaxis.Set(nbinsz,zbins);
   else       fZaxis.Set(nbinsz,0,1);
   fNcells      = (nbinsx+2)*(nbinsy+2)*(nbinsz+2);
   fTsumwy      = fTsumwy2 = fTsumwxy = 0;
   fTsumwz      = fTsumwz2 = fTsumwxz = fTsumwyz = 0;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TH3::~TH3()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy.
 
void TH3::Copy(TObject &obj) const
{
   TH1::Copy(obj);
   ((TH3&)obj).fTsumwy      = fTsumwy;
   ((TH3&)obj).fTsumwy2     = fTsumwy2;
   ((TH3&)obj).fTsumwxy     = fTsumwxy;
   ((TH3&)obj).fTsumwz      = fTsumwz;
   ((TH3&)obj).fTsumwz2     = fTsumwz2;
   ((TH3&)obj).fTsumwxz     = fTsumwxz;
   ((TH3&)obj).fTsumwyz     = fTsumwyz;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Fill histogram with all entries in the buffer.
/// action = -1 histogram is reset and refilled from the buffer (called by THistPainter::Paint)
/// action =  0 histogram is filled from the buffer
/// action =  1 histogram is filled and buffer is deleted
///             The buffer is automatically deleted when the number of entries
///             in the buffer is greater than the number of entries in the histogram
 
Int_t TH3::BufferEmpty(Int_t action)
{
   // do we need to compute the bin size?
   if (!fBuffer) return 0;
   Int_t nbentries = (Int_t)fBuffer[0];
   if (!nbentries) return 0;
   Double_t *buffer = fBuffer;
   if (nbentries < 0) {
      if (action == 0) return 0;
      nbentries  = -nbentries;
      fBuffer=nullptr;
      Reset("ICES");
      fBuffer = buffer;
   }
   const bool xbinAuto = fXaxis.GetXmax() <= fXaxis.GetXmin();
   const bool ybinAuto = fYaxis.GetXmax() <= fYaxis.GetXmin();
   const bool zbinAuto = fZaxis.GetXmax() <= fZaxis.GetXmin();
   if (CanExtendAllAxes() || xbinAuto || ybinAuto || zbinAuto) {
         //find min, max of entries in buffer
         Double_t xmin = xbinAuto ? fBuffer[2] : fXaxis.GetXmin();
         Double_t xmax = xbinAuto ? xmin : fXaxis.GetXmax();
         Double_t ymin = ybinAuto ? fBuffer[3] : fYaxis.GetXmin();
         Double_t ymax = ybinAuto ? ymin : fYaxis.GetXmax();
         Double_t zmin = zbinAuto ? fBuffer[4] : fZaxis.GetXmin();
         Double_t zmax = zbinAuto ? zmin : fZaxis.GetXmax();
         for (Int_t i=1;i<nbentries;i++) {
            if (CanExtendAllAxes() || xbinAuto) {
               Double_t x = fBuffer[4*i+2];
               if (x < xmin) xmin = x;
               if (x > xmax) xmax = x;
            }
            if (CanExtendAllAxes() || ybinAuto) {
               Double_t y = fBuffer[4*i+3];
               if (y < ymin) ymin = y;
               if (y > ymax) ymax = y;
            }
            if (CanExtendAllAxes() || zbinAuto) {
               Double_t z = fBuffer[4*i+4];
               if (z < zmin) zmin = z;
               if (z > zmax) zmax = z;
            }
         }
         if (xbinAuto || ybinAuto || zbinAuto) {
            THLimitsFinder::GetLimitsFinder()->FindGoodLimitsXYZ(
               this, xmin, xmax, ymin, ymax, zmin, zmax, xbinAuto ? 0 : fXaxis.GetNbins(),
               ybinAuto ? 0 : fYaxis.GetNbins(), zbinAuto ? 0 : fZaxis.GetNbins());
         } else {
            fBuffer = nullptr;
            Int_t keep = fBufferSize; fBufferSize = 0;
            if (xmin <  fXaxis.GetXmin()) ExtendAxis(xmin,&fXaxis);
            if (xmax >= fXaxis.GetXmax()) ExtendAxis(xmax,&fXaxis);
            if (ymin <  fYaxis.GetXmin()) ExtendAxis(ymin,&fYaxis);
            if (ymax >= fYaxis.GetXmax()) ExtendAxis(ymax,&fYaxis);
            if (zmin <  fZaxis.GetXmin()) ExtendAxis(zmin,&fZaxis);
            if (zmax >= fZaxis.GetXmax()) ExtendAxis(zmax,&fZaxis);
            fBuffer = buffer;
            fBufferSize = keep;
         }
   }
   fBuffer = nullptr;
 
   for (Int_t i=0;i<nbentries;i++) {
      Fill(buffer[4*i+2],buffer[4*i+3],buffer[4*i+4],buffer[4*i+1]);
   }
   fBuffer = buffer;
 
   if (action > 0) { delete [] fBuffer; fBuffer = nullptr; fBufferSize = 0;}
   else {
      if (nbentries == (Int_t)fEntries) fBuffer[0] = -nbentries;
      else                              fBuffer[0] = 0;
   }
   return nbentries;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Accumulate arguments in buffer. When buffer is full, empty the buffer
///
///  - `fBuffer[0]` = number of entries in buffer
///  - `fBuffer[1]` = w of first entry
///  - `fBuffer[2]` = x of first entry
///  - `fBuffer[3]` = y of first entry
///  - `fBuffer[4]` = z of first entry
 
Int_t TH3::BufferFill(Double_t x, Double_t y, Double_t z, Double_t w)
{
   if (!fBuffer) return -3;
   Int_t nbentries = (Int_t)fBuffer[0];
   if (nbentries < 0) {
      nbentries  = -nbentries;
      fBuffer[0] =  nbentries;
      if (fEntries > 0) {
         Double_t *buffer = fBuffer; fBuffer=nullptr;
         Reset("ICES");
         fBuffer = buffer;
      }
   }
   if (4*nbentries+4 >= fBufferSize) {
      BufferEmpty(1);
      return Fill(x,y,z,w);
   }
   fBuffer[4*nbentries+1] = w;
   fBuffer[4*nbentries+2] = x;
   fBuffer[4*nbentries+3] = y;
   fBuffer[4*nbentries+4] = z;
   fBuffer[0] += 1;
   return -3;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Invalid Fill method
 
Int_t TH3::Fill(Double_t )
{
   Error("Fill", "Invalid signature - do nothing");
   return -1;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by x,y,z by 1 .
///
/// The function returns the corresponding global bin number which has its content
/// incremented by 1
 
Int_t TH3::Fill(Double_t x, Double_t y, Double_t z)
{
   if (fBuffer) return BufferFill(x,y,z,1);
 
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(x);
   biny = fYaxis.FindBin(y);
   binz = fZaxis.FindBin(z);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (fSumw2.fN) ++fSumw2.fArray[bin];
   AddBinContent(bin);
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
 
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (binz == 0 || binz > fZaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   ++fTsumw;
   ++fTsumw2;
   fTsumwx  += x;
   fTsumwx2 += x*x;
   fTsumwy  += y;
   fTsumwy2 += y*y;
   fTsumwxy += x*y;
   fTsumwz  += z;
   fTsumwz2 += z*z;
   fTsumwxz += x*z;
   fTsumwyz += y*z;
   return bin;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by x,y,z by a weight w.
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the cell corresponding to x,y,z.
///
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(Double_t x, Double_t y, Double_t z, Double_t w)
{
   if (fBuffer) return BufferFill(x,y,z,w);
 
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(x);
   biny = fYaxis.FindBin(y);
   binz = fZaxis.FindBin(z);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))  Sumw2();   // must be called before AddBinContent
   if (fSumw2.fN) fSumw2.fArray[bin] += w*w;
   AddBinContent(bin,w);
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (binz == 0 || binz > fZaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   fTsumw   += w;
   fTsumw2  += w*w;
   fTsumwx  += w*x;
   fTsumwx2 += w*x*x;
   fTsumwy  += w*y;
   fTsumwy2 += w*y*y;
   fTsumwxy += w*x*y;
   fTsumwz  += w*z;
   fTsumwz2 += w*z*z;
   fTsumwxz += w*x*z;
   fTsumwyz += w*y*z;
   return bin;
}
 
#ifdef TH3D_FILL_THREADSAFE
////////////////////////////////////////////////////////////////////////////////
/// Atomically increment cell defined by x,y,z by a weight w.
///
/// This function is thread safe, but it cannot be called concurrently with any
/// other function of the histogram.
/// \note This function requires compiling with c++20
/// \note If the weight is not equal to 1, Sumw2() must have been called before starting to fill.
/// \note In contrast to Fill(double,double,double,double), the histogram is not able
///   to extend its own axes, so out-of-range fills will go into overflow.
/// \note Automatic binning is not supported.
void TH3D::FillThreadSafe(Double_t x, Double_t y, Double_t z, Double_t w)
{
   if (fBuffer)
      throw std::logic_error("TH3 cannot be filled atomically when buffer is active.");
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))
      throw std::logic_error(
         "Weighted filling 'Sumw2()' needs to be activated before FillThreadSafe is called with weights");
 
   std::atomic_ref<decltype(fEntries)> atomicEntries{fEntries};
   atomicEntries += 1.;
 
   const auto binx = fXaxis.FindFixBin(x);
   const auto biny = fYaxis.FindFixBin(y);
   const auto binz = fZaxis.FindFixBin(z);
   if (binx < 0 || biny < 0 || binz < 0)
      return;
   const auto bin = binx + (fXaxis.GetNbins() + 2) * (biny + (fYaxis.GetNbins() + 2) * binz);
   if (fSumw2.fN) {
      std::atomic_ref{fSumw2.fArray[bin]} += w * w;
   }
 
   std::atomic_ref{fArray[bin]} += w;
 
   if (binx == 0 || binx > fXaxis.GetNbins() || biny == 0 || biny > fYaxis.GetNbins() || binz == 0 ||
       binz > fZaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour())
         return;
   }
 
   std::atomic_ref{fTsumw} += w;
   std::atomic_ref{fTsumw2} += w * w;
   std::atomic_ref{fTsumwx} += w * x;
   std::atomic_ref{fTsumwx2} += w * x * x;
   std::atomic_ref{fTsumwy} += w * y;
   std::atomic_ref{fTsumwy2} += w * y * y;
   std::atomic_ref{fTsumwxy} += w * x * y;
   std::atomic_ref{fTsumwz} += w * z;
   std::atomic_ref{fTsumwz2} += w * z * z;
   std::atomic_ref{fTsumwxz} += w * x * z;
   std::atomic_ref{fTsumwyz} += w * y * z;
}
#endif
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by namex,namey,namez by a weight w
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the corresponding cell.
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(const char *namex, const char *namey, const char *namez, Double_t w)
{
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(namex);
   biny = fYaxis.FindBin(namey);
   binz = fZaxis.FindBin(namez);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))  Sumw2();   // must be called before AddBinContent
   if (fSumw2.fN) fSumw2.fArray[bin] += w*w;
   AddBinContent(bin,w);
   if (binx == 0 || binx > fXaxis.GetNbins()) return -1;
   if (biny == 0 || biny > fYaxis.GetNbins()) return -1;
   if (binz == 0 || binz > fZaxis.GetNbins()) return -1;
 
   Double_t v = w;
   fTsumw   += v;
   fTsumw2  += v*v;
   // skip computation of the statistics along axis that have labels (can be extended and are alphanumeric)
   UInt_t labelBitMask = GetAxisLabelStatus();
   if (labelBitMask != TH1::kAllAxes) {
      Double_t x = (labelBitMask & TH1::kXaxis) ? 0 : fXaxis.GetBinCenter(binx);
      Double_t y = (labelBitMask & TH1::kYaxis) ? 0 : fYaxis.GetBinCenter(biny);
      Double_t z = (labelBitMask & TH1::kZaxis) ? 0 : fZaxis.GetBinCenter(binz);
      fTsumwx += v * x;
      fTsumwx2 += v * x * x;
      fTsumwy += v * y;
      fTsumwy2 += v * y * y;
      fTsumwxy += v * x * y;
      fTsumwz += v * z;
      fTsumwz2 += v * z * z;
      fTsumwxz += v * x * z;
      fTsumwyz += v * y * z;
   }
   return bin;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by namex,y,namez by a weight w
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the corresponding cell.
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(const char *namex, Double_t y, const char *namez, Double_t w)
{
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(namex);
   biny = fYaxis.FindBin(y);
   binz = fZaxis.FindBin(namez);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))  Sumw2();   // must be called before AddBinContent
   if (fSumw2.fN) fSumw2.fArray[bin] += w*w;
   AddBinContent(bin,w);
   if (binx == 0 || binx > fXaxis.GetNbins()) return -1;
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (binz == 0 || binz > fZaxis.GetNbins()) return -1;
   Double_t v = w;
   fTsumw   += v;
   fTsumw2  += v*v;
   fTsumwy  += v*y;
   fTsumwy2 += v*y*y;
   // skip computation of the statistics along axis that have labels (can be extended and are alphanumeric)
   UInt_t labelBitMask = GetAxisLabelStatus();
   if (labelBitMask != (TH1::kXaxis | TH1::kZaxis) ) {
      Double_t x = (labelBitMask & TH1::kXaxis) ? 0 : fXaxis.GetBinCenter(binx);
      Double_t z = (labelBitMask & TH1::kZaxis) ? 0 : fZaxis.GetBinCenter(binz);
      fTsumwx += v * x;
      fTsumwx2 += v * x * x;
      fTsumwxy += v * x * y;
      fTsumwz += v * z;
      fTsumwz2 += v * z * z;
      fTsumwxz += v * x * z;
      fTsumwyz += v * y * z;
   }
   return bin;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by namex,namey,z by a weight w
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the corresponding cell.
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(const char *namex, const char *namey, Double_t z, Double_t w)
{
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(namex);
   biny = fYaxis.FindBin(namey);
   binz = fZaxis.FindBin(z);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))  Sumw2();   // must be called before AddBinContent
   if (fSumw2.fN) fSumw2.fArray[bin] += w*w;
   AddBinContent(bin,w);
   if (binx == 0 || binx > fXaxis.GetNbins()) return -1;
   if (biny == 0 || biny > fYaxis.GetNbins()) return -1;
   if (binz == 0 || binz > fZaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   Double_t v = w;
   fTsumw   += v;
   fTsumw2  += v*v;
   fTsumwz  += v*z;
   fTsumwz2 += v*z*z;
   // skip computation of the statistics along axis that have labels (can be extended and are alphanumeric)
   UInt_t labelBitMask = GetAxisLabelStatus();
   if (labelBitMask != (TH1::kXaxis | TH1::kYaxis)) {
      Double_t x = (labelBitMask & TH1::kXaxis) ? 0 : fXaxis.GetBinCenter(binx);
      Double_t y = (labelBitMask & TH1::kYaxis) ? 0 : fYaxis.GetBinCenter(biny);
      fTsumwx += v * x;
      fTsumwx2 += v * x * x;
      fTsumwy += v * y;
      fTsumwy2 += v * y * y;
      fTsumwxy += v * x * y;
      fTsumwxz += v * x * z;
      fTsumwyz += v * y * z;
   }
   return bin;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by x,namey,namez by a weight w
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the corresponding cell.
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(Double_t x, const char *namey, const char *namez, Double_t w)
{
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(x);
   biny = fYaxis.FindBin(namey);
   binz = fZaxis.FindBin(namez);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))  Sumw2();   // must be called before AddBinContent
   if (fSumw2.fN) fSumw2.fArray[bin] += w*w;
   AddBinContent(bin,w);
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) return -1;
   if (binz == 0 || binz > fZaxis.GetNbins()) return -1;
 
   Double_t v = w;
   fTsumw += v;
   fTsumw2 += v * v;
   fTsumwx += v * x;
   fTsumwx2 += v * x * x;
   // skip computation of the statistics along axis that have labels (can be extended and are alphanumeric)
   UInt_t labelBitMask = GetAxisLabelStatus();
   if (labelBitMask != (TH1::kYaxis | TH1::kZaxis)) {
      Double_t y = (labelBitMask & TH1::kYaxis) ? 0 : fYaxis.GetBinCenter(biny);
      Double_t z = (labelBitMask & TH1::kZaxis) ? 0 : fZaxis.GetBinCenter(binz);
      fTsumwy += v * y;
      fTsumwy2 += v * y * y;
      fTsumwxy += v * x * y;
      fTsumwz += v * z;
      fTsumwz2 += v * z * z;
      fTsumwxz += v * x * z;
      fTsumwyz += v * y * z;
   }
   return bin;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by namex , y ,z by a weight w
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the corresponding cell.
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(const char * namex, Double_t y, Double_t z, Double_t w)
{
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(namex);
   biny = fYaxis.FindBin(y);
   binz = fZaxis.FindBin(z);
   if (binx < 0 || biny < 0 || binz < 0)
      return -1;
   bin = binx + (fXaxis.GetNbins() + 2) * (biny + (fYaxis.GetNbins() + 2) * binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))
      Sumw2(); // must be called before AddBinContent
   if (fSumw2.fN)
      fSumw2.fArray[bin] += w * w;
   AddBinContent(bin, w);
   if (binx == 0 || binx > fXaxis.GetNbins()) {
         return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour())
         return -1;
   }
   if (binz == 0 || binz > fZaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour())
         return -1;
   }
   Double_t v = w;
   fTsumw += v;
   fTsumw2 += v * v;
   fTsumwy += v * y;
   fTsumwy2 += v * y * y;
   fTsumwz += v * z;
   fTsumwz2 += v * z * z;
   fTsumwyz += v * y * z;
   // skip computation for x axis : for only one axis no need to use bit mask
   if (!fXaxis.CanExtend() || !fXaxis.IsAlphanumeric()) {
      Double_t x = fXaxis.GetBinCenter(binx);
      fTsumwx += v * x;
      fTsumwx2 += v * x * x;
      fTsumwxy += v * x * y;
      fTsumwxz += v * x * z;
   }
   return bin;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by x,namey,z by a weight w
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the corresponding cell.
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(Double_t x, const char *namey, Double_t z, Double_t w)
{
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(x);
   biny = fYaxis.FindBin(namey);
   binz = fZaxis.FindBin(z);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))  Sumw2();   // must be called before AddBinContent
   if (fSumw2.fN) fSumw2.fArray[bin] += w*w;
   AddBinContent(bin,w);
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) return -1;
   if (binz == 0 || binz > fZaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   Double_t v = w;
   fTsumw   += v;
   fTsumw2  += v*v;
   fTsumwx  += v*x;
   fTsumwx2 += v*x*x;
   fTsumwz  += v*z;
   fTsumwz2 += v*z*z;
   fTsumwxz += v*x*z;
   // skip computation for y axis : for only one axis no need to use bit mask
   if (!fYaxis.CanExtend() || !fYaxis.IsAlphanumeric()) {
      Double_t y = fYaxis.GetBinCenter(biny);
      fTsumwy  += v*y;
      fTsumwy2 += v*y*y;
      fTsumwxy += v*x*y;
      fTsumwyz += v*y*z;
   }
 
   return bin;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment cell defined by x,y,namez by a weight w
///
/// If the weight is not equal to 1, the storage of the sum of squares of
///  weights is automatically triggered and the sum of the squares of weights is incremented
///  by w^2 in the corresponding cell.
/// The function returns the corresponding global bin number which has its content
/// incremented by w
 
Int_t TH3::Fill(Double_t x, Double_t y, const char *namez, Double_t w)
{
   Int_t binx, biny, binz, bin;
   fEntries++;
   binx = fXaxis.FindBin(x);
   biny = fYaxis.FindBin(y);
   binz = fZaxis.FindBin(namez);
   if (binx <0 || biny <0 || binz<0) return -1;
   bin  =  binx + (fXaxis.GetNbins()+2)*(biny + (fYaxis.GetNbins()+2)*binz);
   if (!fSumw2.fN && w != 1.0 && !TestBit(TH1::kIsNotW))  Sumw2();   // must be called before AddBinContent
   if (fSumw2.fN) fSumw2.fArray[bin] += w*w;
   AddBinContent(bin,w);
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!GetStatOverflowsBehaviour()) return -1;
   }
   if (binz == 0 || binz > fZaxis.GetNbins()) return -1;
 
   Double_t v = w;
   fTsumw   += v;
   fTsumw2  += v*v;
   fTsumwx  += v*x;
   fTsumwx2 += v*x*x;
   fTsumwy  += v*y;
   fTsumwy2 += v*y*y;
   fTsumwxy += v*x*y;
 
   // skip computation for z axis : for only one axis no need to use bit mask
   if (!fZaxis.CanExtend() || !fZaxis.IsAlphanumeric()) {
      Double_t z = fZaxis.GetBinCenter(binz);
      fTsumwz  += v*z;
      fTsumwz2 += v*z*z;
      fTsumwxz += v*x*z;
      fTsumwyz += v*y*z;
   }
   return bin;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Fill histogram following distribution in function fname.
///
///  @param fname  : Function name used for filling the histogram
///  @param ntimes : number of times the histogram is filled
///  @param rng    : (optional) Random number generator used to sample
///
///   The distribution contained in the function fname (TF1) is integrated
///   over the channel contents.
///   It is normalized to 1.
///   Getting one random number implies:
///     - Generating a random number between 0 and 1 (say r1)
///     - Look in which bin in the normalized integral r1 corresponds to
///     - Fill histogram channel
///   ntimes random numbers are generated
///
/// N.B. By dfault this methods approximates the integral of the function in each bin with the
///      function value at the center of the bin, multiplied by the bin width
///
///  One can also call TF1::GetRandom to get a random variate from a function.
 
void TH3::FillRandom(TF1 *fobj, Int_t ntimes, TRandom * rng)
{
   Int_t bin, binx, biny, binz, ibin, loop;
   Double_t r1, x, y,z, xv[3];
   TF3 *f1 = dynamic_cast<TF3*>( fobj );
   if (!f1) { Error("FillRandom", "Function: %s is not a TF3, is a %s",fobj->GetName(),fobj->IsA()->GetName()); return; }
 
   TAxis & xAxis = fXaxis;
   TAxis & yAxis = fYaxis;
   TAxis & zAxis = fZaxis;
 
   // in case axes of histogram are not defined use the function axis
   if (fXaxis.GetXmax() <= fXaxis.GetXmin()  || fYaxis.GetXmax() <= fYaxis.GetXmin() || fZaxis.GetXmax() <= fZaxis.GetXmin() ) {
      Double_t xmin,xmax,ymin,ymax,zmin,zmax;
      f1->GetRange(xmin,ymin,zmin,xmax,ymax,zmax);
      Info("FillRandom","Using function axis and range ([%g,%g],[%g,%g],[%g,%g])",xmin, xmax,ymin,ymax,zmin,zmax);
      xAxis = *(f1->GetHistogram()->GetXaxis());
      yAxis = *(f1->GetHistogram()->GetYaxis());
      zAxis = *(f1->GetHistogram()->GetZaxis());
   }
 
   //  Allocate temporary space to store the integral and compute integral
   Int_t nbinsx = xAxis.GetNbins();
   Int_t nbinsy = yAxis.GetNbins();
   Int_t nbinsz = zAxis.GetNbins();
   Int_t nxy = nbinsx*nbinsy;
   Int_t nbins  = nbinsx*nbinsy*nbinsz;
 
   Double_t *integral = new Double_t[nbins+1];
   ibin = 0;
   integral[ibin] = 0;
   // approximate integral with function value at bin center
   for (binz=1;binz<=nbinsz;binz++) {
      xv[2] = zAxis.GetBinCenter(binz);
      for (biny=1;biny<=nbinsy;biny++) {
         xv[1] = yAxis.GetBinCenter(biny);
         for (binx=1;binx<=nbinsx;binx++) {
            xv[0] = xAxis.GetBinCenter(binx);
            ibin++;
            Double_t fint = f1->EvalPar(xv, nullptr);
            // uncomment this line to have the integral computation in a bin
            // Double_t fint = f1->Integral(xAxis.GetBinLowEdge(binx), xAxis.GetBinUpEdge(binx),
            //                              yAxis.GetBinLowEdge(biny), yAxis.GetBinUpEdge(biny),
            //                              zAxis.GetBinLowEdge(binz), zAxis.GetBinUpEdge(binz));
            integral[ibin] = integral[ibin-1] + fint;
         }
      }
   }
 
   //  Normalize integral to 1
   if (integral[nbins] == 0 ) {
      delete [] integral;
      Error("FillRandom", "Integral = zero"); return;
   }
   for (bin=1;bin<=nbins;bin++)  integral[bin] /= integral[nbins];
 
   // Start main loop ntimes
   if (fDimension < 2) nbinsy = -1;
   if (fDimension < 3) nbinsz = -1;
   for (loop=0;loop<ntimes;loop++) {
      r1 = (rng) ? rng->Rndm() : gRandom->Rndm();
      ibin = TMath::BinarySearch(nbins,&integral[0],r1);
      binz = ibin/nxy;
      biny = (ibin - nxy*binz)/nbinsx;
      binx = 1 + ibin - nbinsx*(biny + nbinsy*binz);
      if (nbinsz) binz++;
      if (nbinsy) biny++;
      x    = xAxis.GetBinCenter(binx);
      y    = yAxis.GetBinCenter(biny);
      z    = zAxis.GetBinCenter(binz);
      Fill(x,y,z, 1.);
   }
   delete [] integral;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Fill histogram following distribution in histogram h.
///
///  @param h      : Histogram  pointer used for sampling random number
///  @param ntimes : number of times the histogram is filled
///  @param rng    : (optional) Random number generator used for sampling
///
///   The distribution contained in the histogram h (TH3) is integrated
///   over the channel contents.
///   It is normalized to 1.
///   Getting one random number implies:
///     - Generating a random number between 0 and 1 (say r1)
///     - Look in which bin in the normalized integral r1 corresponds to
///     - Fill histogram channel
///   ntimes random numbers are generated
 
void TH3::FillRandom(TH1 *h, Int_t ntimes, TRandom * rng)
{
   if (!h) { Error("FillRandom", "Null histogram"); return; }
   if (fDimension != h->GetDimension()) {
      Error("FillRandom", "Histograms with different dimensions"); return;
   }
 
   if (h->ComputeIntegral() == 0) return;
 
   TH3 *h3 = (TH3*)h;
   Int_t loop;
   Double_t x,y,z;
   for (loop=0;loop<ntimes;loop++) {
      h3->GetRandom3(x,y,z,rng);
      Fill(x,y,z);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Project slices along Z in case of a 3-D histogram, then fit each slice
/// with function f1 and make a 2-d histogram for each fit parameter
/// Only cells in the bin range [binminx,binmaxx] and [binminy,binmaxy] are considered.
/// if f1=0, a gaussian is assumed
/// Before invoking this function, one can set a subrange to be fitted along Z
/// via f1->SetRange(zmin,zmax)
/// The argument option (default="QNR") can be used to change the fit options.
///     "Q" means Quiet mode
///     "N" means do not show the result of the fit
///     "R" means fit the function in the specified function range
///
/// Note that the generated histograms are added to the list of objects
/// in the current directory. It is the user's responsibility to delete
/// these histograms.
///
///  Example: Assume a 3-d histogram h3
///   Root > h3->FitSlicesZ(); produces 4 TH2D histograms
///          with h3_0 containing parameter 0(Constant) for a Gaus fit
///                    of each cell in X,Y projected along Z
///          with h3_1 containing parameter 1(Mean) for a gaus fit
///          with h3_2 containing parameter 2(StdDev)  for a gaus fit
///          with h3_chi2 containing the chisquare/number of degrees of freedom for a gaus fit
///
///   Root > h3->Fit(0,15,22,0,0,10);
///          same as above, but only for bins 15 to 22 along X
///          and only for cells in X,Y for which the corresponding projection
///          along Z has more than cut bins filled.
///
///  NOTE: To access the generated histograms in the current directory, do eg:
///     TH2D *h3_1 = (TH2D*)gDirectory->Get("h3_1");
 
void TH3::FitSlicesZ(TF1 *f1, Int_t binminx, Int_t binmaxx, Int_t binminy, Int_t binmaxy, Int_t cut, Option_t *option)
{
   //Int_t nbinsz  = fZaxis.GetNbins();
 
   // get correct first and last bins for outer axes used in the loop doing the slices
   // when using default values (0,-1) check if an axis range is set in outer axis
   // do same as in DoProjection for inner axis
   auto computeFirstAndLastBin = [](const TAxis  & outerAxis, Int_t &firstbin, Int_t &lastbin) {
      Int_t nbins  = outerAxis.GetNbins();
      if ( lastbin < firstbin && outerAxis.TestBit(TAxis::kAxisRange) ) {
         firstbin = outerAxis.GetFirst();
         lastbin = outerAxis.GetLast();
         // For special case of TAxis::SetRange, when first == 1 and last
         // = N and the range bit has been set, the TAxis will return 0
         // for both.
         if (firstbin == 0 && lastbin == 0)  {
            firstbin = 1;
            lastbin = nbins;
         }
      }
      if (firstbin < 0) firstbin = 0;
      if (lastbin < 0 || lastbin > nbins + 1) lastbin = nbins + 1;
      if (lastbin < firstbin) {firstbin = 0; lastbin = nbins + 1;}
   };
 
   computeFirstAndLastBin(fXaxis, binminx, binmaxx);
   computeFirstAndLastBin(fYaxis, binminy, binmaxy);
 
   // limits for the axis of the fit results histograms are different
   auto computeAxisLimits = [](const TAxis  & outerAxis, Int_t firstbin, Int_t lastbin,
                               Int_t  &nBins, Double_t  &xMin, Double_t  & xMax) {
      Int_t firstOutBin = std::max(firstbin,1);
      Int_t lastOutBin = std::min(lastbin,outerAxis.GetNbins() ) ;
      nBins = lastOutBin-firstOutBin+1;
      xMin = outerAxis.GetBinLowEdge(firstOutBin);
      xMax = outerAxis.GetBinUpEdge(lastOutBin);
      // return first bin that is used in case of variable bin size axis
      return firstOutBin;
   };
   Int_t nbinsX = 0;
   Double_t xMin, xMax = 0;
   Int_t firstBinXaxis = computeAxisLimits(fXaxis, binminx, binmaxx, nbinsX, xMin, xMax);
   Int_t nbinsY = 0;
   Double_t yMin, yMax = 0;
   Int_t firstBinYaxis = computeAxisLimits(fYaxis, binminy, binmaxy, nbinsY, yMin, yMax);
 
   //default is to fit with a gaussian
   if (f1 == nullptr) {
      f1 = (TF1*)gROOT->GetFunction("gaus");
      if (f1 == nullptr) f1 = new TF1("gaus","gaus",fZaxis.GetXmin(),fZaxis.GetXmax());
      else         f1->SetRange(fZaxis.GetXmin(),fZaxis.GetXmax());
   }
   const char *fname = f1->GetName();
   Int_t npar = f1->GetNpar();
   Double_t *parsave = new Double_t[npar];
   f1->GetParameters(parsave);
 
   //Create one 2-d histogram for each function parameter
   Int_t ipar;
   TString name;
   TString title;
   std::vector<TH1*> hlist(npar+1); // include also chi2 histogram
   const TArrayD *xbins = fXaxis.GetXbins();
   const TArrayD *ybins = fYaxis.GetXbins();
   for (ipar=0;ipar<= npar;ipar++) {
      if (ipar < npar) {
         // fitted parameter histograms
         name = TString::Format("%s_%d",GetName(),ipar);
         title = TString::Format("Fitted value of par[%d]=%s",ipar,f1->GetParName(ipar));
      } else {
         // chi2 histograms
         name = TString::Format("%s_chi2",GetName());
         title = "chisquare";
      }
      if (xbins->fN == 0 && ybins->fN == 0) {
         hlist[ipar] = new TH2D(name, title,
                                nbinsX, xMin, xMax,
                                nbinsY, yMin, yMax);
      } else if (xbins->fN > 0 && ybins->fN > 0 ) {
         hlist[ipar] = new TH2D(name, title,
                                nbinsX, &xbins->fArray[firstBinXaxis],
                                nbinsY, &ybins->fArray[firstBinYaxis]);
      }
      // mixed case do not exist for TH3
      R__ASSERT(hlist[ipar]);
 
      hlist[ipar]->GetXaxis()->SetTitle(fXaxis.GetTitle());
      hlist[ipar]->GetYaxis()->SetTitle(fYaxis.GetTitle());
   }
   TH1 * hchi2 = hlist.back();
 
   //Loop on all cells in X,Y generate a projection along Z
   TH1D *hpz = nullptr;
   TString opt(option);
   // add option "N" when fitting the 2D histograms
   opt += " N ";
 
   for (Int_t biny=binminy; biny<=binmaxy; biny++) {
      for (Int_t binx=binminx; binx<=binmaxx; binx++) {
         // use TH3::ProjectionZ
         hpz = ProjectionZ("R_temp",binx,binx,biny,biny);
 
         Double_t nentries = hpz->GetEntries();
         if ( nentries <= 0 || nentries < cut) {
            if (!opt.Contains("Q"))
               Info("FitSlicesZ","Slice (%d,%d) skipped, the number of entries is zero or smaller than the given cut value, n=%f",binx,biny,nentries);
            continue;
         }
         f1->SetParameters(parsave);
         Int_t bin = hlist[0]->FindBin( fXaxis.GetBinCenter(binx), fYaxis.GetBinCenter(biny) );
         if (!opt.Contains("Q")) {
            int ibx,iby,ibz = 0;
            hlist[0]->GetBinXYZ(bin,ibx,iby,ibz);
            Info("DoFitSlices","Slice fit [(%f,%f),(%f,%f)]",hlist[0]->GetXaxis()->GetBinLowEdge(ibx), hlist[0]->GetXaxis()->GetBinUpEdge(ibx),
                                                            hlist[0]->GetYaxis()->GetBinLowEdge(iby), hlist[0]->GetYaxis()->GetBinUpEdge(iby));
         }
         hpz->Fit(fname,opt.Data());
         Int_t npfits = f1->GetNumberFitPoints();
         if (npfits > npar && npfits >= cut) {
            for (ipar=0;ipar<npar;ipar++) {
               hlist[ipar]->SetBinContent(bin,f1->GetParameter(ipar));
               hlist[ipar]->SetBinError(bin,f1->GetParError(ipar));
            }
            hchi2->SetBinContent(bin,f1->GetChisquare()/(npfits-npar));
         }
         else {
            if (!opt.Contains("Q"))
               Info("FitSlicesZ","Fitted slice (%d,%d) skipped, the number of fitted points is too small, n=%d",binx,biny,npfits);
         }
      }
   }
   delete [] parsave;
   delete hpz;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// See comments in TH1::GetBin
 
Int_t TH3::GetBin(Int_t binx, Int_t biny, Int_t binz) const
{
   Int_t ofy = fYaxis.GetNbins() + 1; // code duplication unavoidable because TH3 does not inherit from TH2
   if (biny < 0) biny = 0;
   if (biny > ofy) biny = ofy;
 
   Int_t ofz = fZaxis.GetNbins() + 1; // overflow bin
   if (binz < 0) binz = 0;
   if (binz > ofz) binz = ofz;
 
   return TH1::GetBin(binx) + (fXaxis.GetNbins() + 2) * (biny + (fYaxis.GetNbins() + 2) * binz);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Compute first cell (binx,biny,binz) in the range [firstx,lastx](firsty,lasty][firstz,lastz] for which
/// diff = abs(cell_content-c) <= maxdiff
/// In case several cells in the specified range with diff=0 are found
/// the first cell found is returned in binx,biny,binz.
/// In case several cells in the specified range satisfy diff <=maxdiff
/// the cell with the smallest difference is returned in binx,biny,binz.
/// In all cases the function returns the smallest difference.
///
/// NOTE1: if firstx <= 0, firstx is set to bin 1
///        if (lastx < firstx then firstx is set to the number of bins in X
///        ie if firstx=0 and lastx=0 (default) the search is on all bins in X.
///        if firsty <= 0, firsty is set to bin 1
///        if (lasty < firsty then firsty is set to the number of bins in Y
///        ie if firsty=0 and lasty=0 (default) the search is on all bins in Y.
///        if firstz <= 0, firstz is set to bin 1
///        if (lastz < firstz then firstz is set to the number of bins in Z
///        ie if firstz=0 and lastz=0 (default) the search is on all bins in Z.
/// NOTE2: if maxdiff=0 (default), the first cell with content=c is returned.
 
Double_t TH3::GetBinWithContent3(Double_t c, Int_t &binx, Int_t &biny, Int_t &binz,
                                 Int_t firstx, Int_t lastx,
                                 Int_t firsty, Int_t lasty,
                                 Int_t firstz, Int_t lastz,
                                 Double_t maxdiff) const
{
   if (fDimension != 3) {
      binx = 0;
      biny = 0;
      binz = 0;
      Error("GetBinWithContent3","function is only valid for 3-D histograms");
      return 0;
   }
   if (firstx <= 0) firstx = 1;
   if (lastx < firstx) lastx = fXaxis.GetNbins();
   if (firsty <= 0) firsty = 1;
   if (lasty < firsty) lasty = fYaxis.GetNbins();
   if (firstz <= 0) firstz = 1;
   if (lastz < firstz) lastz = fZaxis.GetNbins();
   Int_t binminx = 0, binminy=0, binminz=0;
   Double_t diff, curmax = 1.e240;
   for (Int_t k=firstz;k<=lastz;k++) {
      for (Int_t j=firsty;j<=lasty;j++) {
         for (Int_t i=firstx;i<=lastx;i++) {
            diff = TMath::Abs(GetBinContent(i,j,k)-c);
            if (diff <= 0) {binx = i; biny=j; binz=k; return diff;}
            if (diff < curmax && diff <= maxdiff) {curmax = diff, binminx=i; binminy=j;binminz=k;}
         }
      }
   }
   binx = binminx;
   biny = binminy;
   binz = binminz;
   return curmax;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return correlation factor between axis1 and axis2.
 
Double_t TH3::GetCorrelationFactor(Int_t axis1, Int_t axis2) const
{
   if (axis1 < 1 || axis2 < 1 || axis1 > 3 || axis2 > 3) {
      Error("GetCorrelationFactor","Wrong parameters");
      return 0;
   }
   if (axis1 == axis2) return 1;
   Double_t stddev1 = GetStdDev(axis1);
   if (stddev1 == 0) return 0;
   Double_t stddev2 = GetStdDev(axis2);
   if (stddev2 == 0) return 0;
   return GetCovariance(axis1,axis2)/stddev1/stddev2;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return covariance between axis1 and axis2.
 
Double_t TH3::GetCovariance(Int_t axis1, Int_t axis2) const
{
   if (axis1 < 1 || axis2 < 1 || axis1 > 3 || axis2 > 3) {
      Error("GetCovariance","Wrong parameters");
      return 0;
   }
   Double_t stats[kNstat];
   GetStats(stats);
   Double_t sumw   = stats[0];
   Double_t sumwx  = stats[2];
   Double_t sumwx2 = stats[3];
   Double_t sumwy  = stats[4];
   Double_t sumwy2 = stats[5];
   Double_t sumwxy = stats[6];
   Double_t sumwz  = stats[7];
   Double_t sumwz2 = stats[8];
   Double_t sumwxz = stats[9];
   Double_t sumwyz = stats[10];
 
   if (sumw == 0) return 0;
   if (axis1 == 1 && axis2 == 1) {
      return TMath::Abs(sumwx2/sumw - sumwx*sumwx/(sumw*sumw));
   }
   if (axis1 == 2 && axis2 == 2) {
      return TMath::Abs(sumwy2/sumw - sumwy*sumwy/(sumw*sumw));
   }
   if (axis1 == 3 && axis2 == 3) {
      return TMath::Abs(sumwz2/sumw - sumwz*sumwz/(sumw*sumw));
   }
   if ((axis1 == 1 && axis2 == 2) || (axis1 == 2 && axis2 == 1)) {
      return sumwxy/sumw - sumwx*sumwy/(sumw*sumw);
   }
   if ((axis1 == 1 && axis2 == 3) || (axis1 == 3 && axis2 == 1)) {
      return sumwxz/sumw - sumwx*sumwz/(sumw*sumw);
   }
   if ((axis1 == 2 && axis2 == 3) || (axis1 == 3 && axis2 == 2)) {
      return sumwyz/sumw - sumwy*sumwz/(sumw*sumw);
   }
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return 3 random numbers along axis x, y and z distributed according
/// to the cell-contents of this 3-dim histogram
/// @param[out] x  reference to random generated x value
/// @param[out] y  reference to random generated y value
/// @param[out] z  reference to random generated z value
/// @param[in] rng (optional) Random number generator pointer used (default is gRandom)
/// @param[in] option (optional) Set it to "width" if your non-uniform bin contents represent a density rather than
/// counts
 
void TH3::GetRandom3(Double_t &x, Double_t &y, Double_t &z, TRandom *rng, Option_t *option)
{
   Int_t nbinsx = GetNbinsX();
   Int_t nbinsy = GetNbinsY();
   Int_t nbinsz = GetNbinsZ();
   Int_t nxy    = nbinsx*nbinsy;
   Int_t nbins  = nxy*nbinsz;
   Double_t integral;
   // compute integral checking that all bins have positive content (see ROOT-5894)
   if (fIntegral) {
      if (fIntegral[nbins + 1] != fEntries)
         integral = ComputeIntegral(true, option);
      else integral = fIntegral[nbins];
   } else {
      integral = ComputeIntegral(true, option);
   }
   if (integral == 0 ) { x = 0; y = 0; z = 0; return;}
   // case histogram has negative bins
   if (integral == TMath::QuietNaN() ) { x = TMath::QuietNaN(); y = TMath::QuietNaN(); z = TMath::QuietNaN(); return;}
 
   if (!rng) rng = gRandom;
   Double_t r1 = rng->Rndm();
   Int_t ibin = TMath::BinarySearch(nbins,fIntegral,(Double_t) r1);
   Int_t binz = ibin/nxy;
   Int_t biny = (ibin - nxy*binz)/nbinsx;
   Int_t binx = ibin - nbinsx*(biny + nbinsy*binz);
   x = fXaxis.GetBinLowEdge(binx+1);
   if (r1 > fIntegral[ibin]) x +=
      fXaxis.GetBinWidth(binx+1)*(r1-fIntegral[ibin])/(fIntegral[ibin+1] - fIntegral[ibin]);
   y = fYaxis.GetBinLowEdge(biny+1) + fYaxis.GetBinWidth(biny+1)*rng->Rndm();
   z = fZaxis.GetBinLowEdge(binz+1) + fZaxis.GetBinWidth(binz+1)*rng->Rndm();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Fill the array stats from the contents of this histogram
/// The array stats must be correctly dimensioned in the calling program.
/// stats[0] = sumw
/// stats[1] = sumw2
/// stats[2] = sumwx
/// stats[3] = sumwx2
/// stats[4] = sumwy
/// stats[5] = sumwy2
/// stats[6] = sumwxy
/// stats[7] = sumwz
/// stats[8] = sumwz2
/// stats[9] = sumwxz
/// stats[10]= sumwyz
 
void TH3::GetStats(Double_t *stats) const
{
   if (fBuffer) ((TH3*)this)->BufferEmpty();
 
   Int_t bin, binx, biny, binz;
   Double_t w,err;
   Double_t x,y,z;
   if ((fTsumw == 0 && fEntries > 0) || fXaxis.TestBit(TAxis::kAxisRange) || fYaxis.TestBit(TAxis::kAxisRange) || fZaxis.TestBit(TAxis::kAxisRange)) {
      for (bin=0;bin<11;bin++) stats[bin] = 0;
 
      Int_t firstBinX = fXaxis.GetFirst();
      Int_t lastBinX  = fXaxis.GetLast();
      Int_t firstBinY = fYaxis.GetFirst();
      Int_t lastBinY  = fYaxis.GetLast();
      Int_t firstBinZ = fZaxis.GetFirst();
      Int_t lastBinZ  = fZaxis.GetLast();
      // include underflow/overflow if TH1::StatOverflows(kTRUE) in case no range is set on the axis
      if (GetStatOverflowsBehaviour()) {
         if ( !fXaxis.TestBit(TAxis::kAxisRange) ) {
            if (firstBinX == 1) firstBinX = 0;
            if (lastBinX ==  fXaxis.GetNbins() ) lastBinX += 1;
         }
         if ( !fYaxis.TestBit(TAxis::kAxisRange) ) {
            if (firstBinY == 1) firstBinY = 0;
            if (lastBinY ==  fYaxis.GetNbins() ) lastBinY += 1;
         }
         if ( !fZaxis.TestBit(TAxis::kAxisRange) ) {
            if (firstBinZ == 1) firstBinZ = 0;
            if (lastBinZ ==  fZaxis.GetNbins() ) lastBinZ += 1;
         }
      }
 
      // check for labels axis . In that case corresponsing statistics do not make sense and it is set to zero
      Bool_t labelXaxis =  ((const_cast<TAxis&>(fXaxis)).GetLabels() && fXaxis.CanExtend() );
      Bool_t labelYaxis =  ((const_cast<TAxis&>(fYaxis)).GetLabels() && fYaxis.CanExtend() );
      Bool_t labelZaxis =  ((const_cast<TAxis&>(fZaxis)).GetLabels() && fZaxis.CanExtend() );
 
      for (binz = firstBinZ; binz <= lastBinZ; binz++) {
         z = (!labelZaxis) ? fZaxis.GetBinCenter(binz) : 0;
         for (biny = firstBinY; biny <= lastBinY; biny++) {
            y = (!labelYaxis) ? fYaxis.GetBinCenter(biny) : 0;
            for (binx = firstBinX; binx <= lastBinX; binx++) {
               bin = GetBin(binx,biny,binz);
               x = (!labelXaxis) ? fXaxis.GetBinCenter(binx) : 0;
               //w   = TMath::Abs(GetBinContent(bin));
               w   = RetrieveBinContent(bin);
               err = TMath::Abs(GetBinError(bin));
               stats[0] += w;
               stats[1] += err*err;
               stats[2] += w*x;
               stats[3] += w*x*x;
               stats[4] += w*y;
               stats[5] += w*y*y;
               stats[6] += w*x*y;
               stats[7] += w*z;
               stats[8] += w*z*z;
               stats[9] += w*x*z;
               stats[10]+= w*y*z;
            }
         }
      }
   } else {
      stats[0] = fTsumw;
      stats[1] = fTsumw2;
      stats[2] = fTsumwx;
      stats[3] = fTsumwx2;
      stats[4] = fTsumwy;
      stats[5] = fTsumwy2;
      stats[6] = fTsumwxy;
      stats[7] = fTsumwz;
      stats[8] = fTsumwz2;
      stats[9] = fTsumwxz;
      stats[10]= fTsumwyz;
   }
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return integral of bin contents. Only bins in the bins range are considered.
/// By default the integral is computed as the sum of bin contents in the range.
/// if option "width" is specified, the integral is the sum of
/// the bin contents multiplied by the bin width in x, y and in z.
 
Double_t TH3::Integral(Option_t *option) const
{
   return Integral(fXaxis.GetFirst(),fXaxis.GetLast(),
      fYaxis.GetFirst(),fYaxis.GetLast(),
      fZaxis.GetFirst(),fZaxis.GetLast(),option);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return integral of bin contents in range [binx1,binx2],[biny1,biny2],[binz1,binz2]
/// for a 3-D histogram
/// By default the integral is computed as the sum of bin contents in the range.
/// if option "width" is specified, the integral is the sum of
/// the bin contents multiplied by the bin width in x, y and in z.
 
Double_t TH3::Integral(Int_t binx1, Int_t binx2, Int_t biny1, Int_t biny2,
                       Int_t binz1, Int_t binz2, Option_t *option) const
{
   Double_t err = 0;
   return DoIntegral(binx1,binx2,biny1,biny2,binz1,binz2,err,option);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return integral of bin contents in range [binx1,binx2],[biny1,biny2],[binz1,binz2]
/// for a 3-D histogram. Calculates also the integral error using error propagation
/// from the bin errors assuming that all the bins are uncorrelated.
/// By default the integral is computed as the sum of bin contents in the range.
/// if option "width" is specified, the integral is the sum of
/// the bin contents multiplied by the bin width in x, y and in z.
 
Double_t TH3::IntegralAndError(Int_t binx1, Int_t binx2, Int_t biny1, Int_t biny2,
                               Int_t binz1, Int_t binz2,
                               Double_t & error, Option_t *option) const
{
   return DoIntegral(binx1,binx2,biny1,biny2,binz1,binz2,error,option,kTRUE);
}
 
////////////////////////////////////////////////////////////////////////////////
///Not yet implemented
 
Double_t TH3::Interpolate(Double_t) const
{
   Error("Interpolate","This function must be called with 3 arguments for a TH3");
   return 0;
}
 
 
////////////////////////////////////////////////////////////////////////////////
///Not yet implemented
 
Double_t TH3::Interpolate(Double_t, Double_t) const
{
   Error("Interpolate","This function must be called with 3 arguments for a TH3");
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Given a point P(x,y,z), Interpolate approximates the value via trilinear interpolation
/// based on the 8 nearest bin center points (corner of the cube surrounding the points).
/// The Algorithm is described in http://en.wikipedia.org/wiki/Trilinear_interpolation.
///
/// The coordinate (x,y,z) must be in the histogram range. If a coordinate falls into the first
/// or last bin of an axis, the histogram is assumed to be constant at the edges. The interpolation
/// proceeds as if the bin "left of" the first bin in x had the same bin content as the first bin x,
/// and similar for the other axes.
 
Double_t TH3::Interpolate(Double_t x, Double_t y, Double_t z) const
{
   Int_t ubx = fXaxis.FindFixBin(x);
   if ( x < fXaxis.GetBinCenter(ubx) ) ubx -= 1;
   Int_t obx = ubx + 1;
 
   Int_t uby = fYaxis.FindFixBin(y);
   if ( y < fYaxis.GetBinCenter(uby) ) uby -= 1;
   Int_t oby = uby + 1;
 
   Int_t ubz = fZaxis.FindFixBin(z);
   if ( z < fZaxis.GetBinCenter(ubz) ) ubz -= 1;
   Int_t obz = ubz + 1;
 
   auto GetBinCenterExtrapolate = [](TAxis const &axis, Int_t index) {
      // Get bin centres if inside the histogram, or return the centre of an imaginary
      // bin that's just outside the histogram, and which is as wide as the last valid bin.
      // We need to make up a number here to not confuse the linear interpolation code below.
      if (index == 0) {
         return axis.GetBinCenter(1) - axis.GetBinWidth(1);
      } else if (index == axis.GetNbins() + 1) {
         return axis.GetBinCenter(axis.GetNbins()) + axis.GetBinWidth(axis.GetNbins());
      } else {
         return axis.GetBinCenter(index);
      }
   };
 
   Double_t xw = GetBinCenterExtrapolate(fXaxis, obx) - GetBinCenterExtrapolate(fXaxis, ubx);
   Double_t yw = GetBinCenterExtrapolate(fYaxis, oby) - GetBinCenterExtrapolate(fYaxis, uby);
   Double_t zw = GetBinCenterExtrapolate(fZaxis, obz) - GetBinCenterExtrapolate(fZaxis, ubz);
 
   Double_t xd = (x - GetBinCenterExtrapolate(fXaxis, ubx)) / xw;
   Double_t yd = (y - GetBinCenterExtrapolate(fYaxis, uby)) / yw;
   Double_t zd = (z - GetBinCenterExtrapolate(fZaxis, ubz)) / zw;
 
   auto GetBinContentNoOverflow = [this](int ix, int iy, int iz) {
      // When a bin is outside the histogram range, return the last value inside
      // the range. That is, make the histogram constant at its edges.
      ix = std::clamp(ix, 1, GetNbinsX());
      iy = std::clamp(iy, 1, GetNbinsY());
      iz = std::clamp(iz, 1, GetNbinsZ());
 
      return GetBinContent(ix, iy, iz);
   };
 
   Double_t v[] = {GetBinContentNoOverflow(ubx, uby, ubz), GetBinContentNoOverflow(ubx, uby, obz),
                   GetBinContentNoOverflow(ubx, oby, ubz), GetBinContentNoOverflow(ubx, oby, obz),
                   GetBinContentNoOverflow(obx, uby, ubz), GetBinContentNoOverflow(obx, uby, obz),
                   GetBinContentNoOverflow(obx, oby, ubz), GetBinContentNoOverflow(obx, oby, obz)};
 
   Double_t i1 = v[0] * (1 - zd) + v[1] * zd;
   Double_t i2 = v[2] * (1 - zd) + v[3] * zd;
   Double_t j1 = v[4] * (1 - zd) + v[5] * zd;
   Double_t j2 = v[6] * (1 - zd) + v[7] * zd;
 
 
   Double_t w1 = i1 * (1 - yd) + i2 * yd;
   Double_t w2 = j1 * (1 - yd) + j2 * yd;
 
 
   Double_t result = w1 * (1 - xd) + w2 * xd;
 
   return result;
}
 
 
////////////////////////////////////////////////////////////////////////////////
///  Statistical test of compatibility in shape between
///  THIS histogram and h2, using Kolmogorov test.
///     Default: Ignore under- and overflow bins in comparison
///
///     option is a character string to specify options
///         "U" include Underflows in test
///         "O" include Overflows
///         "N" include comparison of normalizations
///         "D" Put out a line of "Debug" printout
///         "M" Return the Maximum Kolmogorov distance instead of prob
///
///   The returned function value is the probability of test
///       (much less than one means NOT compatible)
///
///   The KS test uses the distance between the pseudo-CDF's obtained
///   from the histogram. Since in more than 1D the order for generating the pseudo-CDF is
///   arbitrary, we use the pseudo-CDF's obtained from all the possible 6 combinations of the 3 axis.
///   The average of all the maximum  distances obtained is used in the tests.
 
Double_t TH3::KolmogorovTest(const TH1 *h2, Option_t *option) const
{
   TString opt = option;
   opt.ToUpper();
 
   Double_t prb = 0;
   TH1 *h1 = (TH1*)this;
   if (h2 == nullptr) return 0;
   const TAxis *xaxis1 = h1->GetXaxis();
   const TAxis *xaxis2 = h2->GetXaxis();
   const TAxis *yaxis1 = h1->GetYaxis();
   const TAxis *yaxis2 = h2->GetYaxis();
   const TAxis *zaxis1 = h1->GetZaxis();
   const TAxis *zaxis2 = h2->GetZaxis();
   Int_t ncx1   = xaxis1->GetNbins();
   Int_t ncx2   = xaxis2->GetNbins();
   Int_t ncy1   = yaxis1->GetNbins();
   Int_t ncy2   = yaxis2->GetNbins();
   Int_t ncz1   = zaxis1->GetNbins();
   Int_t ncz2   = zaxis2->GetNbins();
 
   // Check consistency of dimensions
   if (h1->GetDimension() != 3 || h2->GetDimension() != 3) {
      Error("KolmogorovTest","Histograms must be 3-D\n");
      return 0;
   }
 
   // Check consistency in number of channels
   if (ncx1 != ncx2) {
      Error("KolmogorovTest","Number of channels in X is different, %d and %d\n",ncx1,ncx2);
      return 0;
   }
   if (ncy1 != ncy2) {
      Error("KolmogorovTest","Number of channels in Y is different, %d and %d\n",ncy1,ncy2);
      return 0;
   }
   if (ncz1 != ncz2) {
      Error("KolmogorovTest","Number of channels in Z is different, %d and %d\n",ncz1,ncz2);
      return 0;
   }
 
   // Check consistency in channel edges
   Bool_t afunc1 = kFALSE;
   Bool_t afunc2 = kFALSE;
   Double_t difprec = 1e-5;
   Double_t diff1 = TMath::Abs(xaxis1->GetXmin() - xaxis2->GetXmin());
   Double_t diff2 = TMath::Abs(xaxis1->GetXmax() - xaxis2->GetXmax());
   if (diff1 > difprec || diff2 > difprec) {
      Error("KolmogorovTest","histograms with different binning along X");
      return 0;
   }
   diff1 = TMath::Abs(yaxis1->GetXmin() - yaxis2->GetXmin());
   diff2 = TMath::Abs(yaxis1->GetXmax() - yaxis2->GetXmax());
   if (diff1 > difprec || diff2 > difprec) {
      Error("KolmogorovTest","histograms with different binning along Y");
      return 0;
   }
   diff1 = TMath::Abs(zaxis1->GetXmin() - zaxis2->GetXmin());
   diff2 = TMath::Abs(zaxis1->GetXmax() - zaxis2->GetXmax());
   if (diff1 > difprec || diff2 > difprec) {
      Error("KolmogorovTest","histograms with different binning along Z");
      return 0;
   }
 
   //   Should we include Uflows, Oflows?
   Int_t ibeg = 1, jbeg = 1, kbeg = 1;
   Int_t iend = ncx1, jend = ncy1, kend = ncz1;
   if (opt.Contains("U")) {ibeg = 0; jbeg = 0; kbeg = 0;}
   if (opt.Contains("O")) {iend = ncx1+1; jend = ncy1+1; kend = ncz1+1;}
 
   Int_t i,j,k,bin;
   Double_t sum1  = 0;
   Double_t sum2  = 0;
   Double_t w1    = 0;
   Double_t w2    = 0;
   for (i = ibeg; i <= iend; i++) {
      for (j = jbeg; j <= jend; j++) {
         for (k = kbeg; k <= kend; k++) {
            bin = h1->GetBin(i,j,k);
            sum1 += h1->GetBinContent(bin);
            sum2 += h2->GetBinContent(bin);
            Double_t ew1   = h1->GetBinError(bin);
            Double_t ew2   = h2->GetBinError(bin);
            w1   += ew1*ew1;
            w2   += ew2*ew2;
         }
      }
   }
 
 
   //    Check that both scatterplots contain events
   if (sum1 == 0) {
      Error("KolmogorovTest","Integral is zero for h1=%s\n",h1->GetName());
      return 0;
   }
   if (sum2 == 0) {
      Error("KolmogorovTest","Integral is zero for h2=%s\n",h2->GetName());
      return 0;
   }
   // calculate the effective entries.
   // the case when errors are zero (w1 == 0 or w2 ==0) are equivalent to
   // compare to a function. In that case the rescaling is done only on sqrt(esum2) or sqrt(esum1)
   Double_t esum1 = 0, esum2 = 0;
   if (w1 > 0)
      esum1 = sum1 * sum1 / w1;
   else
      afunc1 = kTRUE;    // use later for calculating z
 
   if (w2 > 0)
      esum2 = sum2 * sum2 / w2;
   else
      afunc2 = kTRUE;    // use later for calculating z
 
   if (afunc2 && afunc1) {
      Error("KolmogorovTest","Errors are zero for both histograms\n");
      return 0;
   }
 
   //   Find Kolmogorov distance
   //   order is arbitrary take average of all possible 6 starting orders x,y,z
   int order[3] = {0,1,2};
   int binbeg[3];
   int binend[3];
   int ibin[3];
   binbeg[0] = ibeg; binbeg[1] = jbeg; binbeg[2] = kbeg;
   binend[0] = iend; binend[1] = jend; binend[2] = kend;
   Double_t vdfmax[6]; // there are in total 6 combinations
   int icomb = 0;
   Double_t s1 = 1./(6.*sum1);
   Double_t s2 = 1./(6.*sum2);
   Double_t rsum1=0, rsum2=0;
   do {
      // loop on bins
      Double_t dmax = 0;
      for (i = binbeg[order[0] ]; i <= binend[order[0] ]; i++) {
         for ( j = binbeg[order[1] ]; j <= binend[order[1] ]; j++) {
            for ( k = binbeg[order[2] ]; k <= binend[order[2] ]; k++) {
                  ibin[ order[0] ] = i;
                  ibin[ order[1] ] = j;
                  ibin[ order[2] ] = k;
                  bin = h1->GetBin(ibin[0],ibin[1],ibin[2]);
                  rsum1 += s1*h1->GetBinContent(bin);
                  rsum2 += s2*h2->GetBinContent(bin);
                  dmax   = TMath::Max(dmax, TMath::Abs(rsum1-rsum2));
            }
         }
      }
      vdfmax[icomb] = dmax;
      icomb++;
   } while (TMath::Permute(3,order)  );
 
 
   // get average of distances
   Double_t dfmax = TMath::Mean(6,vdfmax);
 
   //    Get Kolmogorov probability
   Double_t factnm;
   if (afunc1)      factnm = TMath::Sqrt(sum2);
   else if (afunc2) factnm = TMath::Sqrt(sum1);
   else             factnm = TMath::Sqrt(sum1*sum2/(sum1+sum2));
   Double_t z  = dfmax*factnm;
 
   prb = TMath::KolmogorovProb(z);
 
   Double_t prb1 = 0, prb2 = 0;
   // option N to combine normalization makes sense if both afunc1 and afunc2 are false
   if (opt.Contains("N")  && !(afunc1 || afunc2 ) ) {
      // Combine probabilities for shape and normalization
      prb1   = prb;
      Double_t d12    = esum1-esum2;
      Double_t chi2   = d12*d12/(esum1+esum2);
      prb2   = TMath::Prob(chi2,1);
      //     see Eadie et al., section 11.6.2
      if (prb > 0 && prb2 > 0) prb = prb*prb2*(1-TMath::Log(prb*prb2));
      else                     prb = 0;
   }
 
   //    debug printout
   if (opt.Contains("D")) {
      printf(" Kolmo Prob  h1 = %s, sum1=%g\n",h1->GetName(),sum1);
      printf(" Kolmo Prob  h2 = %s, sum2=%g\n",h2->GetName(),sum2);
      printf(" Kolmo Probabil = %f, Max Dist = %g\n",prb,dfmax);
      if (opt.Contains("N"))
         printf(" Kolmo Probabil = %f for shape alone, =%f for normalisation alone\n",prb1,prb2);
   }
   // This numerical error condition should never occur:
   if (TMath::Abs(rsum1-1) > 0.002) Warning("KolmogorovTest","Numerical problems with h1=%s\n",h1->GetName());
   if (TMath::Abs(rsum2-1) > 0.002) Warning("KolmogorovTest","Numerical problems with h2=%s\n",h2->GetName());
 
   if (opt.Contains("M"))      return dfmax;  // return average of max distance
 
   return prb;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Project a 3-D histogram into a 1-D histogram along X (integration along Y and Z).
///
///   The projection is always of the type TH1D.
///   The projection is made from summing the cells along the Y and Z axes
///   ranging from iymin to iymax and izmin to izmax included.
///   By default, underflow and overflows are included in both the Y and Z axis.
///   By Setting iymin=1 and iymax=NbinsY the underflow and/or overflow in Y will be excluded
///   By setting izmin=1 and izmax=NbinsZ the underflow and/or overflow in Z will be excluded
///
///   if option "e" is specified, the errors are computed.
///   if option "d" is specified, the projection is drawn in the current pad.
///   if option "o" original axis range of the target axes will be
///   kept, but only bins inside the selected range will be filled.
///
///   if option "width" is specified, each bin content is multiplied
///   by its YZ bin-area during projection
///
///   NOTE that if a TH1D named "name" exists in the current directory or pad
///   the histogram is reset and filled again with the projected contents of the TH3.
///
///  implemented using Project3D
 
TH1D *TH3::ProjectionX(const char *name, Int_t iymin, Int_t iymax,
                       Int_t izmin, Int_t izmax, Option_t *option) const
{
   // in case of default name append the parent name
   TString hname = name;
   if (hname == "_px") hname = TString::Format("%s%s", GetName(), name);
   TString title =  TString::Format("%s ( Projection X )",GetTitle());
 
   // when projecting in X outer axis are Y and Z (order is important. It is defined in the DoProject1D function)
   return DoProject1D(hname, title, iymin, iymax, izmin, izmax, &fXaxis, &fYaxis, &fZaxis, option);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Project a 3-D histogram into a 1-D histogram along Y (integration along X and Z).
///
///   The projection is always of the type TH1D.
///   The projection is made from summing the cells along the X and Z axes
///   ranging from ixmin to ixmax and izmin to izmax included.
///   By default, underflow and overflow are included in both the X and Z axis.
///   By setting ixmin=1 and ixmax=NbinsX the underflow and/or overflow in X will be excluded
///   By setting izmin=1 and izmax=NbinsZ the underflow and/or overflow in Z will be excluded
///
///   if option "e" is specified, the errors are computed.
///   if option "d" is specified, the projection is drawn in the current pad.
///   if option "o" original axis range of the target axes will be
///   kept, but only bins inside the selected range will be filled.
///
///   if option "width" is specified, each bin content is multiplied
///   by its XZ bin-area during projection
///
///   NOTE that if a TH1D named "name" exists in the current directory or pad,
///   the histogram is reset and filled again with the projected contents of the TH3.
///
///  implemented using Project3D
 
TH1D *TH3::ProjectionY(const char *name, Int_t ixmin, Int_t ixmax,
                       Int_t izmin, Int_t izmax, Option_t *option) const
{
   TString hname = name;
   if (hname == "_py") hname = TString::Format("%s%s", GetName(), name);
   TString title =  TString::Format("%s ( Projection Y )",GetTitle());
 
   // when projecting in Y outer axis are X and Z (order is important. It is defined in the DoProject1D function)
   return DoProject1D(hname, title, ixmin, ixmax, izmin, izmax, &fYaxis, &fXaxis, &fZaxis, option);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Project a 3-D histogram into a 1-D histogram along Z (integration along X and Y).
///
///   The projection is always of the type TH1D.
///   The projection is made from summing the cells along the X and Y axis
///   ranging from ixmin to ixmax and iymin to iymax included.
///   By default, bins 1 to nx and 1 to ny  are included
///   By default, underflow and overflow are included in both the X and Y axis.
///   By Setting ixmin=1 and ixmax=NbinsX the underflow and/or overflow in X will be excluded
///   By setting iymin=1 and/or iymax=NbinsY the underflow and/or overflow in Y will be excluded
///
///   if option "e" is specified, the errors are computed.
///   if option "d" is specified, the projection is drawn in the current pad.
///   if option "o" original axis range of the target axes will be
///   kept, but only bins inside the selected range will be filled.
///
///   if option "width" is specified, each bin content is multiplied
///   by its XY bin-area during projection
///
///   NOTE that if a TH1D named "name" exists in the current directory or pad,
///   the histogram is reset and filled again with the projected contents of the TH3.
///
///  implemented using Project3D
 
TH1D *TH3::ProjectionZ(const char *name, Int_t ixmin, Int_t ixmax,
                       Int_t iymin, Int_t iymax, Option_t *option) const
{
 
   TString hname = name;
   if (hname == "_pz") hname = TString::Format("%s%s", GetName(), name);
   TString title =  TString::Format("%s ( Projection Z )",GetTitle());
 
   // when projecting in Z outer axis are X and Y (order is important. It is defined in the DoProject1D function)
   return DoProject1D(hname, title, ixmin, ixmax, iymin, iymax, &fZaxis, &fXaxis, &fYaxis, option);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// internal method performing the projection to 1D histogram
/// called from TH3::Project3D
 
TH1D *TH3::DoProject1D(const char* name, const char * title, int imin1, int imax1, int imin2, int imax2,
                       const TAxis* projAxis, const TAxis * axis1, const TAxis * axis2, Option_t * option) const
{
 
   TString opt = option;
   opt.ToLower();
 
   // save previous axis range and bits
   // Int_t iminOld1 = axis1->GetFirst();
   // Int_t imaxOld1 = axis1->GetLast();
   // Int_t iminOld2 = axis2->GetFirst();
   // Int_t imaxOld2 = axis2->GetLast();
   // Bool_t hadRange1 = axis1->TestBit(TAxis::kAxisRange);
   // Bool_t hadRange2 = axis2->TestBit(TAxis::kAxisRange);
 
   // need to cast-away constness to set range
   TAxis out1(*axis1);
   TAxis out2(*axis2);
   // const_cast<TAxis *>(axis1)->SetRange(imin1, imax1);
   // const_cast<TAxis*>(axis2)->SetRange(imin2,imax2);
   out1.SetRange(imin1, imax1);
   out2.SetRange(imin2, imax2);
 
   Bool_t computeErrors = GetSumw2N();
   if (opt.Contains("e") ) {
      computeErrors = kTRUE;
      opt.Remove(opt.First("e"),1);
   }
   Bool_t originalRange = kFALSE;
   if (opt.Contains('o') ) {
      originalRange = kTRUE;
      opt.Remove(opt.First("o"),1);
   }
 
   TH1D * h1 = DoProject1D(name, title, projAxis, &out1, &out2, computeErrors, originalRange,true,true,opt.Contains("width"));
 
   // // restore original range
   // if (axis1->TestBit(TAxis::kAxisRange)) {
   //    if (hadRange1) const_cast<TAxis*>(axis1)->SetRange(iminOld1,imaxOld1);
   // if (axis2->TestBit(TAxis::kAxisRange)) const_cast<TAxis*>(axis2)->SetRange(iminOld2,imaxOld2);
   // // we need also to restore the original bits
 
   // draw in current pad
   if (h1 && opt.Contains("d")) {
      opt.Remove(opt.First("d"),1);
      TVirtualPad::TContext ctxt(gROOT->GetSelectedPad(), true, true);
      if (!gPad || !gPad->FindObject(h1)) {
         h1->Draw(opt);
      } else {
         h1->Paint(opt);
      }
   }
 
   return h1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// internal method performing the projection to 1D histogram
/// called from other TH3::DoProject1D
 
TH1D *TH3::DoProject1D(const char* name, const char * title, const TAxis* projX,
                       const TAxis * out1, const TAxis * out2,
                       bool computeErrors, bool originalRange,
                       bool useUF, bool useOF, bool useWidth) const
{
   // Create the projection histogram
   TH1D *h1 = nullptr;
 
   // Get range to use as well as bin limits
   // Projected range must be inside and not outside original one (ROOT-8781)
   Int_t ixmin = std::max(projX->GetFirst(),1);
   Int_t ixmax = std::min(projX->GetLast(),projX->GetNbins());
   Int_t nx = ixmax-ixmin+1;
 
   // Create the histogram, either reseting a preexisting one
   TObject *h1obj = gROOT->FindObject(name);
   if (h1obj && h1obj->InheritsFrom(TH1::Class())) {
      if (h1obj->IsA() != TH1D::Class() ) {
         Error("DoProject1D","Histogram with name %s must be a TH1D and is a %s",name,h1obj->ClassName());
         return nullptr;
      }
      h1 = (TH1D*)h1obj;
      // reset histogram and re-set the axis in any case
      h1->Reset();
      const TArrayD *bins = projX->GetXbins();
      if ( originalRange )
      {
         if (bins->fN == 0) {
            h1->SetBins(projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         } else {
            h1->SetBins(projX->GetNbins(),bins->fArray);
         }
      } else {
         if (bins->fN == 0) {
            h1->SetBins(nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         } else {
            h1->SetBins(nx,&bins->fArray[ixmin-1]);
         }
      }
   }
 
   if (!h1) {
      const TArrayD *bins = projX->GetXbins();
      if ( originalRange )
      {
         if (bins->fN == 0) {
            h1 = new TH1D(name,title,projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         } else {
            h1 = new TH1D(name,title,projX->GetNbins(),bins->fArray);
         }
      } else {
         if (bins->fN == 0) {
            h1 = new TH1D(name,title,nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         } else {
            h1 = new TH1D(name,title,nx,&bins->fArray[ixmin-1]);
         }
      }
   }
 
   // Copy the axis attributes and the axis labels if needed.
   h1->GetXaxis()->ImportAttributes(projX);
   THashList* labels = projX->GetLabels();
   if (labels) {
      TIter iL(labels);
      TObjString* lb;
      Int_t i = 1;
      while ((lb=(TObjString*)iL())) {
         h1->GetXaxis()->SetBinLabel(i,lb->String().Data());
         i++;
      }
   }
   h1->SetLineColor(this->GetLineColor());
   h1->SetFillColor(this->GetFillColor());
   h1->SetMarkerColor(this->GetMarkerColor());
   h1->SetMarkerStyle(this->GetMarkerStyle());
 
   // Activate errors
   if ( computeErrors && (h1->GetSumw2N() != h1->GetNcells() ) ) h1->Sumw2();
 
   // Set references to the axies in case out1 or out2 ar enot provided
   // and one can use the histogram axis given projX
   if (out1 == nullptr && out2 == nullptr) {
       if (projX == GetXaxis()) {
         out1 = GetYaxis();
         out2 = GetZaxis();
      } else if (projX == GetYaxis()) {
         out1 = GetXaxis();
         out2 = GetZaxis();
      } else {
         out1 = GetXaxis();
         out2 = GetYaxis();
      }
   }
   R__ASSERT(out1 != nullptr && out2 != nullptr);
 
   Int_t *refX = nullptr, *refY = nullptr, *refZ = nullptr;
   Int_t ixbin, out1bin, out2bin;
   if (projX == GetXaxis()) {
      refX = &ixbin;
      refY = &out1bin;
      refZ = &out2bin;
   }
   if (projX == GetYaxis()) {
      refX = &out1bin;
      refY = &ixbin;
      refZ = &out2bin;
   }
   if (projX == GetZaxis()) {
      refX = &out1bin;
      refY = &out2bin;
      refZ = &ixbin;
   }
   R__ASSERT (refX != nullptr && refY != nullptr && refZ != nullptr);
 
   // Fill the projected histogram excluding underflow/overflows if considered in the option
   // if specified in the option (by default they considered)
   Double_t totcont  = 0;
 
   Int_t out1min = out1->GetFirst();
   Int_t out1max = out1->GetLast();
   // GetFirst(), GetLast() can return (0,0) when the range bit is set artificially (see TAxis::SetRange)
 //if (out1min == 0 && out1max == 0) { out1min = 1; out1max = out1->GetNbins(); }
   // correct for underflow/overflows
   if (useUF && !out1->TestBit(TAxis::kAxisRange) )  out1min -= 1;
   if (useOF && !out1->TestBit(TAxis::kAxisRange) )  out1max += 1;
   Int_t out2min = out2->GetFirst();
   Int_t out2max = out2->GetLast();
//   if (out2min == 0 && out2max == 0) { out2min = 1; out2max = out2->GetNbins(); }
   if (useUF && !out2->TestBit(TAxis::kAxisRange) )  out2min -= 1;
   if (useOF && !out2->TestBit(TAxis::kAxisRange) )  out2max += 1;
 
   // if the out axis has labels and is extendable, temporary make it non-extendable to avoid adding extra bins
   Bool_t extendable = projX->CanExtend();
   if ( labels && extendable ) h1->GetXaxis()->SetCanExtend(kFALSE);
   for (ixbin=0;ixbin<=1+projX->GetNbins();ixbin++) {
      if ( projX->TestBit(TAxis::kAxisRange) && ( ixbin < ixmin || ixbin > ixmax )) continue;
 
      Double_t cont = 0;
      Double_t err2 = 0;
 
      // loop on the bins to be integrated (outbin should be called inbin)
      for (out1bin = out1min; out1bin <= out1max; out1bin++) {
         for (out2bin = out2min; out2bin <= out2max; out2bin++) {
 
            Int_t bin = GetBin(*refX, *refY, *refZ);
 
            // sum the bin contents and errors if needed
            double step = useWidth ? out1->GetBinWidth(out1bin) * out2->GetBinWidth(out2bin) : 1;
            cont += RetrieveBinContent(bin) * step;
            if (computeErrors) {
               Double_t exyz = GetBinError(bin) * step;
               err2 += exyz*exyz;
            }
         }
      }
      Int_t ix    = h1->FindBin( projX->GetBinCenter(ixbin) );
      h1->SetBinContent(ix ,cont);
      if (computeErrors) h1->SetBinError(ix, TMath::Sqrt(err2) );
      // sum all content
      totcont += cont;
 
   }
   if ( labels ) h1->GetXaxis()->SetCanExtend(extendable);
 
   // since we use a combination of fill and SetBinError we need to reset and recalculate the statistics
   // for weighted histograms otherwise sumw2 will be wrong.
   // We  can keep the original statistics from the TH3 if the projected sumw is consistent with original one
   // i.e. when no events are thrown away
   bool resetStats = true;
   double eps = 1.E-12;
   if (IsA() == TH3F::Class() ) eps = 1.E-6;
   if (fTsumw != 0 && TMath::Abs( fTsumw - totcont) <  TMath::Abs(fTsumw) * eps) resetStats = false;
 
   bool resetEntries = resetStats;
   // entries are calculated using underflow/overflow. If excluded entries must be reset
   resetEntries |= !useUF || !useOF;
 
 
   if (!resetStats) {
      Double_t stats[kNstat];
      GetStats(stats);
      if ( projX == GetYaxis() ) {
         stats[2] = stats[4];
         stats[3] = stats[5];
      }
      else if  ( projX == GetZaxis() ) {
         stats[2] = stats[7];
         stats[3] = stats[8];
      }
      h1->PutStats(stats);
   }
   else {
      // reset statistics
      h1->ResetStats();
   }
   if (resetEntries) {
      // in case of error calculation (i.e. when Sumw2() is set)
      // use the effective entries for the entries
      // since this  is the only way to estimate them
      Double_t entries =  TMath::Floor( totcont + 0.5); // to avoid numerical rounding
      if (computeErrors) entries = h1->GetEffectiveEntries();
      h1->SetEntries( entries );
   }
   else {
      h1->SetEntries( fEntries );
   }
 
   return h1;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// internal method performing the projection to a 2D histogram
/// called from TH3::Project3D
 
TH2D *TH3::DoProject2D(const char* name, const char * title, const TAxis* projX, const TAxis* projY,
                    bool computeErrors, bool originalRange,
                    bool useUF, bool useOF, bool useWidth) const
{
   TH2D *h2 = nullptr;
 
   // Get range to use as well as bin limits
   Int_t ixmin = std::max(projX->GetFirst(),1);
   Int_t ixmax = std::min(projX->GetLast(),projX->GetNbins());
   Int_t iymin = std::max(projY->GetFirst(),1);
   Int_t iymax = std::min(projY->GetLast(),projY->GetNbins());
 
   Int_t nx = ixmax-ixmin+1;
   Int_t ny = iymax-iymin+1;
 
   // Create the histogram, either reseting a preexisting one
   //  or creating one from scratch.
   // Does an object with the same name exists?
   TObject *h2obj = gROOT->FindObject(name);
   if (h2obj && h2obj->InheritsFrom(TH1::Class())) {
      if ( h2obj->IsA() != TH2D::Class() ) {
         Error("DoProject2D","Histogram with name %s must be a TH2D and is a %s",name,h2obj->ClassName());
         return nullptr;
      }
      h2 = (TH2D*)h2obj;
      // reset histogram and its axes
      h2->Reset();
      const TArrayD *xbins = projX->GetXbins();
      const TArrayD *ybins = projY->GetXbins();
      if ( originalRange ) {
         h2->SetBins(projY->GetNbins(),projY->GetXmin(),projY->GetXmax()
                     ,projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         // set bins for mixed axis do not exists - need to set afterwards the variable bins
         if (ybins->fN != 0)
            h2->GetXaxis()->Set(projY->GetNbins(),&ybins->fArray[iymin-1]);
         if (xbins->fN != 0)
            h2->GetYaxis()->Set(projX->GetNbins(),&xbins->fArray[ixmin-1]);
      } else {
         h2->SetBins(ny,projY->GetBinLowEdge(iymin),projY->GetBinUpEdge(iymax)
                     ,nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         if (ybins->fN != 0)
            h2->GetXaxis()->Set(ny,&ybins->fArray[iymin-1]);
         if (xbins->fN != 0)
            h2->GetYaxis()->Set(nx,&xbins->fArray[ixmin-1]);
      }
   }
 
 
   if (!h2) {
      const TArrayD *xbins = projX->GetXbins();
      const TArrayD *ybins = projY->GetXbins();
      if ( originalRange )
      {
         if (xbins->fN == 0 && ybins->fN == 0) {
            h2 = new TH2D(name,title,projY->GetNbins(),projY->GetXmin(),projY->GetXmax()
                          ,projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         } else if (ybins->fN == 0) {
            h2 = new TH2D(name,title,projY->GetNbins(),projY->GetXmin(),projY->GetXmax()
                          ,projX->GetNbins(),&xbins->fArray[ixmin-1]);
         } else if (xbins->fN == 0) {
            h2 = new TH2D(name,title,projY->GetNbins(),&ybins->fArray[iymin-1]
                          ,projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         } else {
            h2 = new TH2D(name,title,projY->GetNbins(),&ybins->fArray[iymin-1],projX->GetNbins(),&xbins->fArray[ixmin-1]);
         }
      } else {
         if (xbins->fN == 0 && ybins->fN == 0) {
            h2 = new TH2D(name,title,ny,projY->GetBinLowEdge(iymin),projY->GetBinUpEdge(iymax)
                          ,nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         } else if (ybins->fN == 0) {
            h2 = new TH2D(name,title,ny,projY->GetBinLowEdge(iymin),projY->GetBinUpEdge(iymax)
                          ,nx,&xbins->fArray[ixmin-1]);
         } else if (xbins->fN == 0) {
            h2 = new TH2D(name,title,ny,&ybins->fArray[iymin-1]
                          ,nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         } else {
            h2 = new TH2D(name,title,ny,&ybins->fArray[iymin-1],nx,&xbins->fArray[ixmin-1]);
         }
      }
   }
 
   // Copy the axis attributes and the axis labels if needed.
   THashList* labels1 = nullptr;
   THashList* labels2 = nullptr;
   // "xy"
   h2->GetXaxis()->ImportAttributes(projY);
   h2->GetYaxis()->ImportAttributes(projX);
   labels1 = projY->GetLabels();
   labels2 = projX->GetLabels();
   if (labels1) {
      TIter iL(labels1);
      TObjString* lb;
      Int_t i = 1;
      while ((lb=(TObjString*)iL())) {
         h2->GetXaxis()->SetBinLabel(i,lb->String().Data());
         i++;
      }
   }
   if (labels2) {
      TIter iL(labels2);
      TObjString* lb;
      Int_t i = 1;
      while ((lb=(TObjString*)iL())) {
         h2->GetYaxis()->SetBinLabel(i,lb->String().Data());
         i++;
      }
   }
   h2->SetLineColor(this->GetLineColor());
   h2->SetFillColor(this->GetFillColor());
   h2->SetMarkerColor(this->GetMarkerColor());
   h2->SetMarkerStyle(this->GetMarkerStyle());
 
   // Activate errors
   if ( computeErrors && (h2->GetSumw2N() != h2->GetNcells()) ) h2->Sumw2();
 
   // Set references to the axis, so that the bucle has no branches.
   const TAxis* out = nullptr;
   if ( projX != GetXaxis() && projY != GetXaxis() ) {
      out = GetXaxis();
   } else if ( projX != GetYaxis() && projY != GetYaxis() ) {
      out = GetYaxis();
   } else {
      out = GetZaxis();
   }
 
   Int_t *refX = nullptr, *refY = nullptr, *refZ = nullptr;
   Int_t ixbin, iybin, outbin;
   if ( projX == GetXaxis() && projY == GetYaxis() ) { refX = &ixbin;  refY = &iybin;  refZ = &outbin; }
   if ( projX == GetYaxis() && projY == GetXaxis() ) { refX = &iybin;  refY = &ixbin;  refZ = &outbin; }
   if ( projX == GetXaxis() && projY == GetZaxis() ) { refX = &ixbin;  refY = &outbin; refZ = &iybin;  }
   if ( projX == GetZaxis() && projY == GetXaxis() ) { refX = &iybin;  refY = &outbin; refZ = &ixbin;  }
   if ( projX == GetYaxis() && projY == GetZaxis() ) { refX = &outbin; refY = &ixbin;  refZ = &iybin;  }
   if ( projX == GetZaxis() && projY == GetYaxis() ) { refX = &outbin; refY = &iybin;  refZ = &ixbin;  }
   R__ASSERT (refX != nullptr && refY != nullptr && refZ != nullptr);
 
   // Fill the projected histogram excluding underflow/overflows if considered in the option
   // if specified in the option (by default they considered)
   Double_t totcont  = 0;
 
   Int_t outmin = out->GetFirst();
   Int_t outmax = out->GetLast();
   // GetFirst(), GetLast() can return (0,0) when the range bit is set artificially (see TAxis::SetRange)
   if (outmin == 0 && outmax == 0) { outmin = 1; outmax = out->GetNbins(); }
   // correct for underflow/overflows
   if (useUF && !out->TestBit(TAxis::kAxisRange) )  outmin -= 1;
   if (useOF && !out->TestBit(TAxis::kAxisRange) )  outmax += 1;
 
   for (ixbin=0;ixbin<=1+projX->GetNbins();ixbin++) {
      if ( projX->TestBit(TAxis::kAxisRange) && ( ixbin < ixmin || ixbin > ixmax )) continue;
      Int_t ix = h2->GetYaxis()->FindBin( projX->GetBinCenter(ixbin) );
 
      for (iybin=0;iybin<=1+projY->GetNbins();iybin++) {
         if ( projY->TestBit(TAxis::kAxisRange) && ( iybin < iymin || iybin > iymax )) continue;
         Int_t iy = h2->GetXaxis()->FindBin( projY->GetBinCenter(iybin) );
 
         Double_t cont = 0;
         Double_t err2 = 0;
 
         // loop on the bins to be integrated (outbin should be called inbin)
         for (outbin = outmin; outbin <= outmax; outbin++) {
 
            Int_t bin = GetBin(*refX,*refY,*refZ);
 
            // sum the bin contents and errors if needed
            double step = useWidth ? out->GetBinWidth(outbin) : 1;
            cont += RetrieveBinContent(bin) * step;
            if (computeErrors) {
               Double_t exyz = GetBinError(bin) * step;
               err2 += exyz*exyz;
            }
 
         }
 
         // remember axis are inverted
         h2->SetBinContent(iy , ix, cont);
         if (computeErrors) h2->SetBinError(iy, ix, TMath::Sqrt(err2) );
         // sum all content
         totcont += cont;
 
      }
   }
 
   // since we use fill we need to reset and recalculate the statistics (see comment in DoProject1D )
   // or keep original statistics if consistent sumw2
   bool resetStats = true;
   double eps = 1.E-12;
   if (IsA() == TH3F::Class() ) eps = 1.E-6;
   if (fTsumw != 0 && TMath::Abs( fTsumw - totcont) <  TMath::Abs(fTsumw) * eps) resetStats = false;
 
   bool resetEntries = resetStats;
   // entries are calculated using underflow/overflow. If excluded entries must be reset
   resetEntries |= !useUF || !useOF;
 
   if (!resetStats) {
      Double_t stats[kNstat];
      Double_t oldst[kNstat]; // old statistics
      for (Int_t i = 0; i < kNstat; ++i) { oldst[i] = 0; }
      GetStats(oldst);
      std::copy(oldst,oldst+kNstat,stats);
      // not that projX refer to Y axis and projX refer to the X axis of projected histogram
      // nothing to do for projection in Y vs X
      if ( projY == GetXaxis() && projX == GetZaxis() ) {  // case XZ
         stats[4] = oldst[7];
         stats[5] = oldst[8];
         stats[6] = oldst[9];
      }
      if ( projY == GetYaxis() ) {
         stats[2] = oldst[4];
         stats[3] = oldst[5];
         if ( projX == GetXaxis() )  { // case YX
            stats[4] = oldst[2];
            stats[5] = oldst[3];
         }
         if ( projX == GetZaxis() )  { // case YZ
            stats[4] = oldst[7];
            stats[5] = oldst[8];
            stats[6] = oldst[10];
         }
      }
      else if  ( projY == GetZaxis() ) {
         stats[2] = oldst[7];
         stats[3] = oldst[8];
         if ( projX == GetXaxis() )  { // case ZX
            stats[4] = oldst[2];
            stats[5] = oldst[3];
            stats[6] = oldst[9];
         }
         if ( projX == GetYaxis() )  { // case ZY
            stats[4] = oldst[4];
            stats[5] = oldst[5];
            stats[6] = oldst[10];
         }
      }
      // set the new statistics
      h2->PutStats(stats);
   }
   else {
      // recalculate the statistics
      h2->ResetStats();
   }
 
   if (resetEntries) {
      // use the effective entries for the entries
      // since this  is the only way to estimate them
      Double_t entries =  h2->GetEffectiveEntries();
      if (!computeErrors) entries = TMath::Floor( entries + 0.5); // to avoid numerical rounding
      h2->SetEntries( entries );
   }
   else {
      h2->SetEntries( fEntries );
   }
 
 
   return h2;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Project a 3-d histogram into 1 or 2-d histograms depending on the
/// option parameter, which may contain a combination of the characters x,y,z,e
///  - option = "x" return the x projection into a TH1D histogram
///  - option = "y" return the y projection into a TH1D histogram
///  - option = "z" return the z projection into a TH1D histogram
///  - option = "xy" return the x versus y projection into a TH2D histogram
///  - option = "yx" return the y versus x projection into a TH2D histogram
///  - option = "xz" return the x versus z projection into a TH2D histogram
///  - option = "zx" return the z versus x projection into a TH2D histogram
///  - option = "yz" return the y versus z projection into a TH2D histogram
///  - option = "zy" return the z versus y projection into a TH2D histogram
///
/// NB: the notation "a vs b" means "a" vertical and "b" horizontal
///
/// option = "o" original axis range of the target axes will be
///   kept, but only bins inside the selected range will be filled.
///
/// If option contains the string "e", errors are computed
///
/// If option "width" is specified, each bin content is multiplied
/// by its width (area) along the integrated dimension(s)
///
/// The projection is made for the selected bins only.
/// To select a bin range along an axis, use TAxis::SetRange, eg
///    h3.GetYaxis()->SetRange(23,56);
///
/// NOTE 1: The generated histogram is named th3name + option
/// eg if the TH3* h histogram is named "myhist", then
/// h->Project3D("xy"); produces a TH2D histogram named "myhist_xy"
/// if a histogram of the same type already exists, it is overwritten.
/// The following sequence
///    h->Project3D("xy");
///    h->Project3D("xy2");
///  will generate two TH2D histograms named "myhist_xy" and "myhist_xy2"
///  A different name can be generated by attaching a string to the option
///  For example h->Project3D("name_xy") will generate an histogram with the name:  h3dname_name_xy.
///
///  NOTE 2: If an histogram of the same type and with the same name already exists in current Directory,
///  the histogram is reset and filled again with the projected contents of the TH3.
///
///  NOTE 3: The number of entries in the projected histogram is estimated from the number of
///  effective entries for all the cells included in the projection.
///
///  NOTE 4: underflow/overflow are included by default in the projection
///  To exclude underflow and/or overflow (for both axis in case of a projection to a 1D histogram) use option "NUF" and/or "NOF"
///  With SetRange() you can have all bins except underflow/overflow only if you set the axis bit range as
///  following after having called SetRange:  axis->SetRange(1, axis->GetNbins());
///
///  NOTE 5: If TH1::AddDirectory is set to false, a new histogram is always created and the ownership of the
///  returned pointer is delegated to the user. Be sure in this case to call `delete` on it after it's no longer needed,
///  to avoid memory leaks.
 
TH1 *TH3::Project3D(Option_t *option) const
{
   TString opt = option;
   TString extra_name = option;
   Int_t underscore = extra_name.Last('_');
   if (underscore > 0) {
      extra_name.Remove(underscore,extra_name.Length()-underscore);
      opt.Remove(0,underscore+1);
    }
   opt.ToLower();
   bool useWidth = opt.Contains("width");
   Int_t pcase = 0;
   TString ptype;
   if (opt.Contains("x"))  { pcase = 1; ptype = "x"; }
   if (opt.Contains("y"))  { pcase = 2; ptype = "y"; }
   if (opt.Contains("z"))  { pcase = 3; ptype = "z"; }
   if (opt.Contains("xy")) { pcase = 4; ptype = "xy"; }
   if (opt.Contains("yx")) { pcase = 5; ptype = "yx"; }
   if (opt.Contains("xz")) { pcase = 6; ptype = "xz"; }
   if (opt.Contains("zx")) { pcase = 7; ptype = "zx"; }
   if (opt.Contains("yz")) { pcase = 8; ptype = "yz"; }
   if (opt.Contains("zy")) { pcase = 9; ptype = "zy"; }
 
   if (pcase == 0) {
      Error("Project3D","No projection axis specified - return a NULL pointer");
      return nullptr;
   }
   // do not remove ptype from opt to use later in the projected histo name
 
   Bool_t computeErrors = GetSumw2N();
   if (opt.Contains("e") ) {
      computeErrors = kTRUE;
      opt.Remove(opt.First("e"),1);
   }
 
   Bool_t useUF = kTRUE;
   Bool_t useOF = kTRUE;
   if (opt.Contains("nuf") ) {
      useUF = kFALSE;
      opt.Remove(opt.Index("nuf"),3);
   }
   if (opt.Contains("nof") ) {
      useOF = kFALSE;
      opt.Remove(opt.Index("nof"),3);
   }
 
   Bool_t originalRange = kFALSE;
   if (opt.Contains('o') ) {
      originalRange = kTRUE;
      opt.Remove(opt.First("o"),1);
   }
 
 
   // Create the projection histogram
   TH1 *h = nullptr;
 
   TString name = GetName();
   TString title = GetTitle();
   if (underscore > 0) {
      name  += "_";
      name  += extra_name;
   }
   name  += "_";   name  += opt;
   title += " ";   title += ptype; title += " projection";
 
   switch (pcase) {
      case 1:
         // "x"
         h = DoProject1D(name, title, this->GetXaxis(), nullptr, nullptr,
                        computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 2:
         // "y"
         h = DoProject1D(name, title, this->GetYaxis(), nullptr, nullptr,
                         computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 3:
         // "z"
         h = DoProject1D(name, title, this->GetZaxis(), nullptr, nullptr,
                         computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 4:
         // "xy"
         h = DoProject2D(name, title, this->GetXaxis(),this->GetYaxis(),
                       computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 5:
         // "yx"
         h = DoProject2D(name, title, this->GetYaxis(),this->GetXaxis(),
                       computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 6:
         // "xz"
         h = DoProject2D(name, title, this->GetXaxis(),this->GetZaxis(),
                       computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 7:
         // "zx"
         h = DoProject2D(name, title, this->GetZaxis(),this->GetXaxis(),
                       computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 8:
         // "yz"
         h = DoProject2D(name, title, this->GetYaxis(),this->GetZaxis(),
                       computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
      case 9:
         // "zy"
         h = DoProject2D(name, title, this->GetZaxis(),this->GetYaxis(),
                       computeErrors, originalRange, useUF, useOF, useWidth);
         break;
 
   }
 
   // draw in current pad
   if (h && opt.Contains("d")) {
      opt.Remove(opt.First("d"),1);
      TVirtualPad::TContext ctxt(gROOT->GetSelectedPad(), true, true);
      if (!gPad || !gPad->FindObject(h)) {
         h->Draw(opt);
      } else {
         h->Paint(opt);
      }
   }
 
   return h;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// internal function to fill the bins of the projected profile 2D histogram
/// called from DoProjectProfile2D
 
void TH3::DoFillProfileProjection(TProfile2D * p2,
                                  const TAxis & a1, const TAxis & a2, const TAxis & a3,
                                  Int_t bin1, Int_t bin2, Int_t bin3,
                                  Int_t inBin, Bool_t useWeights ) const {
   Double_t cont = GetBinContent(inBin);
   if (!cont) return;
   TArrayD & binSumw2 = *(p2->GetBinSumw2());
   if (useWeights && binSumw2.fN <= 0) useWeights = false;
   if (!useWeights) p2->SetBit(TH1::kIsNotW);  // to use Fill for setting the bin contents of the Profile
   // the following fill update wrongly the fBinSumw2- need to save it before
   Double_t u = a1.GetBinCenter(bin1);
   Double_t v = a2.GetBinCenter(bin2);
   Double_t w = a3.GetBinCenter(bin3);
   Int_t outBin = p2->FindBin(u, v);
   if (outBin <0) return;
   Double_t tmp = 0;
   if ( useWeights ) tmp = binSumw2.fArray[outBin];
   p2->Fill( u , v, w, cont);
   if (useWeights ) binSumw2.fArray[outBin] = tmp + fSumw2.fArray[inBin];
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// internal method to project to a 2D Profile
/// called from TH3::Project3DProfile
 
TProfile2D *TH3::DoProjectProfile2D(const char *name, const char *title, const TAxis *projX, const TAxis *projY,
                                    bool originalRange, bool useUF, bool useOF, bool useWidth) const
{
   // Get the ranges where we will work.
   Int_t ixmin = std::max(projX->GetFirst(),1);
   Int_t ixmax = std::min(projX->GetLast(),projX->GetNbins());
   Int_t iymin = std::max(projY->GetFirst(),1);
   Int_t iymax = std::min(projY->GetLast(),projY->GetNbins());
 
   Int_t nx = ixmax-ixmin+1;
   Int_t ny = iymax-iymin+1;
 
   // Create the projected profiles
   TProfile2D *p2 = nullptr;
 
   // Create the histogram, either reseting a preexisting one
   // Does an object with the same name exists?
   TObject *p2obj = gROOT->FindObject(name);
   if (p2obj && p2obj->InheritsFrom(TH1::Class())) {
      if (p2obj->IsA() != TProfile2D::Class() ) {
         Error("DoProjectProfile2D","Histogram with name %s must be a TProfile2D and is a %s",name,p2obj->ClassName());
         return nullptr;
      }
      p2 = (TProfile2D*)p2obj;
      // reset existing profile and re-set bins
      p2->Reset();
      const TArrayD *xbins = projX->GetXbins();
      const TArrayD *ybins = projY->GetXbins();
      if ( originalRange ) {
         p2->SetBins(projY->GetNbins(),projY->GetXmin(),projY->GetXmax()
                     ,projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         // set bins for mixed axis do not exists - need to set afterwards the variable bins
         if (ybins->fN != 0)
            p2->GetXaxis()->Set(projY->GetNbins(),&ybins->fArray[iymin-1]);
         if (xbins->fN != 0)
            p2->GetYaxis()->Set(projX->GetNbins(),&xbins->fArray[ixmin-1]);
      } else {
         p2->SetBins(ny,projY->GetBinLowEdge(iymin),projY->GetBinUpEdge(iymax)
                     ,nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         if (ybins->fN != 0)
            p2->GetXaxis()->Set(ny,&ybins->fArray[iymin-1]);
         if (xbins->fN != 0)
            p2->GetYaxis()->Set(nx,&xbins->fArray[ixmin-1]);
      }
   }
 
   if (!p2) {
      const TArrayD *xbins = projX->GetXbins();
      const TArrayD *ybins = projY->GetXbins();
      if ( originalRange ) {
         if (xbins->fN == 0 && ybins->fN == 0) {
            p2 = new TProfile2D(name,title,projY->GetNbins(),projY->GetXmin(),projY->GetXmax()
                                ,projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         } else if (ybins->fN == 0) {
            p2 = new TProfile2D(name,title,projY->GetNbins(),projY->GetXmin(),projY->GetXmax()
                                ,projX->GetNbins(),&xbins->fArray[ixmin-1]);
         } else if (xbins->fN == 0) {
            p2 = new TProfile2D(name,title,projY->GetNbins(),&ybins->fArray[iymin-1]
                                ,projX->GetNbins(),projX->GetXmin(),projX->GetXmax());
         } else {
            p2 = new TProfile2D(name,title,projY->GetNbins(),&ybins->fArray[iymin-1],projX->GetNbins(),&xbins->fArray[ixmin-1]);
         }
      } else {
         if (xbins->fN == 0 && ybins->fN == 0) {
            p2 = new TProfile2D(name,title,ny,projY->GetBinLowEdge(iymin),projY->GetBinUpEdge(iymax)
                                ,nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         } else if (ybins->fN == 0) {
            p2 = new TProfile2D(name,title,ny,projY->GetBinLowEdge(iymin),projY->GetBinUpEdge(iymax)
                                ,nx,&xbins->fArray[ixmin-1]);
         } else if (xbins->fN == 0) {
            p2 = new TProfile2D(name,title,ny,&ybins->fArray[iymin-1]
                                ,nx,projX->GetBinLowEdge(ixmin),projX->GetBinUpEdge(ixmax));
         } else {
            p2 = new TProfile2D(name,title,ny,&ybins->fArray[iymin-1],nx,&xbins->fArray[ixmin-1]);
         }
      }
   }
 
   // Copy the axis attributes and the axis labels if needed
   p2->GetXaxis()->ImportAttributes(projY);
   p2->GetYaxis()->ImportAttributes(projX);
   THashList* labelsX = projY->GetLabels();
   if (labelsX) {
      TIter iL(labelsX);
      TObjString* lb;
      Int_t i = 1;
      while ((lb=(TObjString*)iL())) {
         p2->GetXaxis()->SetBinLabel(i,lb->String().Data());
         ++i;
      }
   }
   THashList* labelsY = projX->GetLabels();
   if (labelsY) {
      TIter iL(labelsY);
      TObjString* lb;
      Int_t i = 1;
      while ((lb=(TObjString*)iL())) {
         p2->GetYaxis()->SetBinLabel(i,lb->String().Data());
         ++i;
      }
   }
 
   // Set references to the axis, so that the loop has no branches.
   const TAxis* outAxis = nullptr;
   if ( projX != GetXaxis() && projY != GetXaxis() ) {
      outAxis = GetXaxis();
   } else if ( projX != GetYaxis() && projY != GetYaxis() ) {
      outAxis = GetYaxis();
   } else {
      outAxis = GetZaxis();
   }
 
   // Weights management
   bool useWeights = (GetSumw2N() > 0);
   // store sum of w2 in profile if histo is weighted
   if (useWeights && (p2->GetBinSumw2()->fN != p2->GetNcells() ) ) p2->Sumw2();
 
   // Set references to the bins, so that the loop has no branches.
   Int_t *refX = nullptr, *refY = nullptr, *refZ = nullptr;
   Int_t ixbin, iybin, outbin;
   if ( projX == GetXaxis() && projY == GetYaxis() ) { refX = &ixbin;  refY = &iybin;  refZ = &outbin; }
   if ( projX == GetYaxis() && projY == GetXaxis() ) { refX = &iybin;  refY = &ixbin;  refZ = &outbin; }
   if ( projX == GetXaxis() && projY == GetZaxis() ) { refX = &ixbin;  refY = &outbin; refZ = &iybin;  }
   if ( projX == GetZaxis() && projY == GetXaxis() ) { refX = &iybin;  refY = &outbin; refZ = &ixbin;  }
   if ( projX == GetYaxis() && projY == GetZaxis() ) { refX = &outbin; refY = &ixbin;  refZ = &iybin;  }
   if ( projX == GetZaxis() && projY == GetYaxis() ) { refX = &outbin; refY = &iybin;  refZ = &ixbin;  }
   R__ASSERT (refX != nullptr && refY != nullptr && refZ != nullptr);
 
   Int_t outmin = outAxis->GetFirst();
   Int_t outmax = outAxis->GetLast();
   // GetFirst, GetLast can return underflow or overflow bins
   // correct for underflow/overflows
   if (useUF && !outAxis->TestBit(TAxis::kAxisRange) )  outmin -= 1;
   if (useOF && !outAxis->TestBit(TAxis::kAxisRange) )  outmax += 1;
 
   TArrayD & binSumw2 = *(p2->GetBinSumw2());
   if (useWeights && binSumw2.fN <= 0) useWeights = false;
   if (!useWeights) p2->SetBit(TH1::kIsNotW);
 
   // Call specific method for the projection
   for (ixbin=0;ixbin<=1+projX->GetNbins();ixbin++) {
      if ( (ixbin < ixmin || ixbin > ixmax) && projX->TestBit(TAxis::kAxisRange)) continue;
      for ( iybin=0;iybin<=1+projY->GetNbins();iybin++) {
         if ( (iybin < iymin || iybin > iymax) && projX->TestBit(TAxis::kAxisRange)) continue;
 
         // profile output bin
         Int_t poutBin = p2->FindBin(projY->GetBinCenter(iybin), projX->GetBinCenter(ixbin));
         if (poutBin <0) continue;
         // loop on the bins to be integrated (outbin should be called inbin)
         for (outbin = outmin; outbin <= outmax; outbin++) {
 
            Int_t bin = GetBin(*refX,*refY,*refZ);
 
            //DoFillProfileProjection(p2, *projY, *projX, *outAxis, iybin, ixbin, outbin, bin, useWeights);
            double step = useWidth ? outAxis->GetBinWidth(outbin) : 1;
            Double_t cont = RetrieveBinContent(bin) * step;
            if (!cont) continue;
 
            Double_t tmp = 0;
            // the following fill update wrongly the fBinSumw2- need to save it before
            if ( useWeights ) tmp = binSumw2.fArray[poutBin];
            p2->Fill( projY->GetBinCenter(iybin) , projX->GetBinCenter(ixbin), outAxis->GetBinCenter(outbin), cont);
            if (useWeights ) binSumw2.fArray[poutBin] = tmp + fSumw2.fArray[bin];
 
         }
      }
   }
 
   // recompute statistics for the projected profiles
   // forget about preserving old statistics
   bool resetStats = true;
   Double_t stats[kNstat];
   // reset statistics
   if (resetStats)
      for (Int_t i=0;i<kNstat;i++) stats[i] = 0;
 
   p2->PutStats(stats);
   Double_t entries = fEntries;
   // recalculate the statistics
   if (resetStats) {
      entries =  p2->GetEffectiveEntries();
      if (!useWeights) entries = TMath::Floor( entries + 0.5); // to avoid numerical rounding
      p2->SetEntries( entries );
   }
 
   p2->SetEntries(entries);
 
   return p2;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Project a 3-d histogram into a 2-d profile histograms depending
/// on the option parameter
/// option may contain a combination of the characters x,y,z
/// option = "xy" return the x versus y projection into a TProfile2D histogram
/// option = "yx" return the y versus x projection into a TProfile2D histogram
/// option = "xz" return the x versus z projection into a TProfile2D histogram
/// option = "zx" return the z versus x projection into a TProfile2D histogram
/// option = "yz" return the y versus z projection into a TProfile2D histogram
/// option = "zy" return the z versus y projection into a TProfile2D histogram
/// NB: the notation "a vs b" means "a" vertical and "b" horizontal
///
/// option = "o" original axis range of the target axes will be
///   kept, but only bins inside the selected range will be filled.
///
/// if option "width" is specified, each bin content is multiplied
/// by its bin-width across integrated dimension during projection
///
/// The projection is made for the selected bins only.
/// To select a bin range along an axis, use TAxis::SetRange, eg
///    h3.GetYaxis()->SetRange(23,56);
///
/// NOTE 1: The generated histogram is named th3name + "_p" + option
/// eg if the TH3* h histogram is named "myhist", then
/// h->Project3D("xy"); produces a TProfile2D histogram named "myhist_pxy".
/// The following sequence
///    h->Project3DProfile("xy");
///    h->Project3DProfile("xy2");
///  will generate two TProfile2D histograms named "myhist_pxy" and "myhist_pxy2"
///  So, passing additional characters in the option string one can customize the name.
///
///  NOTE 2: If a profile of the same type already exists with compatible axes,
///  the profile is reset and filled again with the projected contents of the TH3.
///  In the case of axes incompatibility, an error is reported and a NULL pointer is returned.
///
///  NOTE 3: The number of entries in the projected profile is estimated from the number of
///  effective entries for all the cells included in the projection.
///
///  NOTE 4: underflow/overflow are by default excluded from the projection
///  (Note that this is a different default behavior compared to the projection to an histogram)
///  To include the underflow and/or overflow use option "UF" and/or "OF"
 
TProfile2D *TH3::Project3DProfile(Option_t *option) const
{
   TString opt = option;
   opt.ToLower();
   Bool_t useWidth = opt.Contains("width");
   Int_t pcase = 0;
   TString ptype;
   if (opt.Contains("xy")) { pcase = 4; ptype = "xy"; }
   if (opt.Contains("yx")) { pcase = 5; ptype = "yx"; }
   if (opt.Contains("xz")) { pcase = 6; ptype = "xz"; }
   if (opt.Contains("zx")) { pcase = 7; ptype = "zx"; }
   if (opt.Contains("yz")) { pcase = 8; ptype = "yz"; }
   if (opt.Contains("zy")) { pcase = 9; ptype = "zy"; }
 
   if (pcase == 0) {
      Error("Project3D","No projection axis specified - return a NULL pointer");
      return nullptr;
   }
   // do not remove ptype from opt to use later in the projected histo name
 
   Bool_t useUF = kFALSE;
   if (opt.Contains("uf") ) {
      useUF = kTRUE;
      opt.Remove(opt.Index("uf"),2);
   }
   Bool_t useOF = kFALSE;
   if (opt.Contains("of") ) {
      useOF = kTRUE;
      opt.Remove(opt.Index("of"),2);
   }
 
   Bool_t originalRange = kFALSE;
   if (opt.Contains('o') ) {
      originalRange = kTRUE;
      opt.Remove(opt.First("o"),1);
   }
 
   // Create the projected profile
   TProfile2D *p2 = nullptr;
   TString name = GetName();
   TString title = GetTitle();
   name  += "_p";   name  += opt;  // opt may include a user defined name
   title += " profile ";   title += ptype; title += " projection";
 
   // Call the method with the specific projected axes.
   switch (pcase) {
      case 4:
         // "xy"
         p2 = DoProjectProfile2D(name, title, GetXaxis(), GetYaxis(), originalRange, useUF, useOF, useWidth);
         break;
 
      case 5:
         // "yx"
         p2 = DoProjectProfile2D(name, title, GetYaxis(), GetXaxis(), originalRange, useUF, useOF, useWidth);
         break;
 
      case 6:
         // "xz"
         p2 = DoProjectProfile2D(name, title, GetXaxis(), GetZaxis(), originalRange, useUF, useOF, useWidth);
         break;
 
      case 7:
         // "zx"
         p2 = DoProjectProfile2D(name, title, GetZaxis(), GetXaxis(), originalRange, useUF, useOF, useWidth);
         break;
 
      case 8:
         // "yz"
         p2 = DoProjectProfile2D(name, title, GetYaxis(), GetZaxis(), originalRange, useUF, useOF, useWidth);
         break;
 
      case 9:
         // "zy"
         p2 = DoProjectProfile2D(name, title, GetZaxis(), GetYaxis(), originalRange, useUF, useOF, useWidth);
         break;
 
   }
 
   return p2;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Replace current statistics with the values in array stats
 
void TH3::PutStats(Double_t *stats)
{
   TH1::PutStats(stats);
   fTsumwy  = stats[4];
   fTsumwy2 = stats[5];
   fTsumwxy = stats[6];
   fTsumwz  = stats[7];
   fTsumwz2 = stats[8];
   fTsumwxz = stats[9];
   fTsumwyz = stats[10];
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Rebin only the X axis
/// see Rebin3D
 
TH3 *TH3::RebinX(Int_t ngroup, const char *newname)
{
  return Rebin3D(ngroup, 1, 1, newname);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Rebin only the Y axis
/// see Rebin3D
 
TH3 *TH3::RebinY(Int_t ngroup, const char *newname)
{
  return Rebin3D(1, ngroup, 1, newname);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Rebin only the Z axis
/// see Rebin3D
 
TH3 *TH3::RebinZ(Int_t ngroup, const char *newname)
{
  return Rebin3D(1, 1, ngroup, newname);
 
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Rebin this histogram grouping nxgroup/nygroup/nzgroup bins along the xaxis/yaxis/zaxis together.
///
///   if newname is not blank a new temporary histogram hnew is created.
///   else the current histogram is modified (default)
///   The parameter nxgroup/nygroup indicate how many bins along the xaxis/yaxis of this
///   have to me merged into one bin of hnew
///   If the original histogram has errors stored (via Sumw2), the resulting
///   histograms has new errors correctly calculated.
///
///   examples: if hpxpy is an existing TH3 histogram with 40 x 40 x 40 bins
///     hpxpypz->Rebin3D();  // merges two bins along the xaxis and yaxis in one in hpxpypz
///                          // Carefull: previous contents of hpxpy are lost
///     hpxpypz->RebinX(5);  //merges five bins along the xaxis in one in hpxpypz
///     TH3 *hnew = hpxpypz->RebinY(5,"hnew"); // creates a new histogram hnew
///                                          // merging 5 bins of h1 along the yaxis in one bin
///
///   NOTE : If nxgroup/nygroup is not an exact divider of the number of bins,
///          along the xaxis/yaxis the top limit(s) of the rebinned histogram
///          is changed to the upper edge of the xbin=newxbins*nxgroup resp.
///          ybin=newybins*nygroup and the corresponding bins are added to
///          the overflow bin.
///          Statistics will be recomputed from the new bin contents.
 
TH3 *TH3::Rebin3D(Int_t nxgroup, Int_t nygroup, Int_t nzgroup, const char *newname)
{
   Int_t i,j,k,xbin,ybin,zbin;
   Int_t nxbins  = fXaxis.GetNbins();
   Int_t nybins  = fYaxis.GetNbins();
   Int_t nzbins  = fZaxis.GetNbins();
   Double_t xmin  = fXaxis.GetXmin();
   Double_t xmax  = fXaxis.GetXmax();
   Double_t ymin  = fYaxis.GetXmin();
   Double_t ymax  = fYaxis.GetXmax();
   Double_t zmin  = fZaxis.GetXmin();
   Double_t zmax  = fZaxis.GetXmax();
   if ((nxgroup <= 0) || (nxgroup > nxbins)) {
      Error("Rebin", "Illegal value of nxgroup=%d",nxgroup);
      return nullptr;
   }
   if ((nygroup <= 0) || (nygroup > nybins)) {
      Error("Rebin", "Illegal value of nygroup=%d",nygroup);
      return nullptr;
   }
   if ((nzgroup <= 0) || (nzgroup > nzbins)) {
      Error("Rebin", "Illegal value of nzgroup=%d",nzgroup);
      return nullptr;
   }
 
   Int_t newxbins = nxbins/nxgroup;
   Int_t newybins = nybins/nygroup;
   Int_t newzbins = nzbins/nzgroup;
 
   // Save old bin contents into a new array
   Double_t entries = fEntries;
   Double_t *oldBins = new Double_t[fNcells];
   for (Int_t ibin = 0; ibin < fNcells; ibin++) {
      oldBins[ibin] = RetrieveBinContent(ibin);
   }
   Double_t *oldSumw2 = nullptr;
   if (fSumw2.fN != 0) {
      oldSumw2 = new Double_t[fNcells];
      for (Int_t ibin = 0; ibin < fNcells; ibin++) {
         oldSumw2[ibin] = fSumw2.fArray[ibin];
      }
   }
 
   // create a clone of the old histogram if newname is specified
   TH3 *hnew = this;
   if (newname && strlen(newname)) {
      hnew = (TH3*)Clone();
      hnew->SetName(newname);
   }
 
   // save original statistics
   Double_t stat[kNstat];
   GetStats(stat);
   bool resetStat = false;
 
 
   // change axis specs and rebuild bin contents array
   if (newxbins*nxgroup != nxbins) {
      xmax = fXaxis.GetBinUpEdge(newxbins*nxgroup);
      resetStat = true; //stats must be reset because top bins will be moved to overflow bin
   }
   if (newybins*nygroup != nybins) {
      ymax = fYaxis.GetBinUpEdge(newybins*nygroup);
      resetStat = true; //stats must be reset because top bins will be moved to overflow bin
   }
   if (newzbins*nzgroup != nzbins) {
      zmax = fZaxis.GetBinUpEdge(newzbins*nzgroup);
      resetStat = true; //stats must be reset because top bins will be moved to overflow bin
   }
   // save the TAttAxis members (reset by SetBins) for x axis
   Int_t    nXdivisions  = fXaxis.GetNdivisions();
   Color_t  xAxisColor   = fXaxis.GetAxisColor();
   Color_t  xLabelColor  = fXaxis.GetLabelColor();
   Style_t  xLabelFont   = fXaxis.GetLabelFont();
   Float_t  xLabelOffset = fXaxis.GetLabelOffset();
   Float_t  xLabelSize   = fXaxis.GetLabelSize();
   Float_t  xTickLength  = fXaxis.GetTickLength();
   Float_t  xTitleOffset = fXaxis.GetTitleOffset();
   Float_t  xTitleSize   = fXaxis.GetTitleSize();
   Color_t  xTitleColor  = fXaxis.GetTitleColor();
   Style_t  xTitleFont   = fXaxis.GetTitleFont();
   // save the TAttAxis members (reset by SetBins) for y axis
   Int_t    nYdivisions  = fYaxis.GetNdivisions();
   Color_t  yAxisColor   = fYaxis.GetAxisColor();
   Color_t  yLabelColor  = fYaxis.GetLabelColor();
   Style_t  yLabelFont   = fYaxis.GetLabelFont();
   Float_t  yLabelOffset = fYaxis.GetLabelOffset();
   Float_t  yLabelSize   = fYaxis.GetLabelSize();
   Float_t  yTickLength  = fYaxis.GetTickLength();
   Float_t  yTitleOffset = fYaxis.GetTitleOffset();
   Float_t  yTitleSize   = fYaxis.GetTitleSize();
   Color_t  yTitleColor  = fYaxis.GetTitleColor();
   Style_t  yTitleFont   = fYaxis.GetTitleFont();
   // save the TAttAxis members (reset by SetBins) for z axis
   Int_t    nZdivisions  = fZaxis.GetNdivisions();
   Color_t  zAxisColor   = fZaxis.GetAxisColor();
   Color_t  zLabelColor  = fZaxis.GetLabelColor();
   Style_t  zLabelFont   = fZaxis.GetLabelFont();
   Float_t  zLabelOffset = fZaxis.GetLabelOffset();
   Float_t  zLabelSize   = fZaxis.GetLabelSize();
   Float_t  zTickLength  = fZaxis.GetTickLength();
   Float_t  zTitleOffset = fZaxis.GetTitleOffset();
   Float_t  zTitleSize   = fZaxis.GetTitleSize();
   Color_t  zTitleColor  = fZaxis.GetTitleColor();
   Style_t  zTitleFont   = fZaxis.GetTitleFont();
 
   // copy merged bin contents (ignore under/overflows)
   if (nxgroup != 1 || nygroup != 1 || nzgroup != 1) {
      if (fXaxis.GetXbins()->GetSize() > 0 || fYaxis.GetXbins()->GetSize() > 0 || fZaxis.GetXbins()->GetSize() > 0) {
         // variable bin sizes in x or y, don't treat both cases separately
         Double_t *xbins = new Double_t[newxbins+1];
         for (i = 0; i <= newxbins; ++i) xbins[i] = fXaxis.GetBinLowEdge(1+i*nxgroup);
         Double_t *ybins = new Double_t[newybins+1];
         for (i = 0; i <= newybins; ++i) ybins[i] = fYaxis.GetBinLowEdge(1+i*nygroup);
         Double_t *zbins = new Double_t[newzbins+1];
         for (i = 0; i <= newzbins; ++i) zbins[i] = fZaxis.GetBinLowEdge(1+i*nzgroup);
         hnew->SetBins(newxbins,xbins, newybins, ybins, newzbins, zbins);//changes also errors array (if any)
         delete [] xbins;
         delete [] ybins;
         delete [] zbins;
      } else {
         hnew->SetBins(newxbins, xmin, xmax, newybins, ymin, ymax, newzbins, zmin, zmax);//changes also errors array
      }
 
      Double_t binContent, binSumw2;
      Int_t oldxbin = 1;
      Int_t oldybin = 1;
      Int_t oldzbin = 1;
      Int_t bin;
      for (xbin = 1; xbin <= newxbins; xbin++) {
         oldybin=1;
         oldzbin=1;
         for (ybin = 1; ybin <= newybins; ybin++) {
            oldzbin=1;
            for (zbin = 1; zbin <= newzbins; zbin++) {
               binContent = 0;
               binSumw2   = 0;
               for (i = 0; i < nxgroup; i++) {
                  if (oldxbin+i > nxbins) break;
                  for (j =0; j < nygroup; j++) {
                     if (oldybin+j > nybins) break;
                     for (k =0; k < nzgroup; k++) {
                        if (oldzbin+k > nzbins) break;
                        //get global bin (same conventions as in TH1::GetBin(xbin,ybin)
                        bin = oldxbin + i + (oldybin + j)*(nxbins + 2) + (oldzbin + k)*(nxbins + 2)*(nybins + 2);
                        binContent += oldBins[bin];
                        if (oldSumw2) binSumw2 += oldSumw2[bin];
                     }
                  }
               }
               Int_t ibin = hnew->GetBin(xbin,ybin,zbin);  // new bin number
               hnew->SetBinContent(ibin, binContent);
               if (oldSumw2) hnew->fSumw2.fArray[ibin] = binSumw2;
               oldzbin += nzgroup;
            }
            oldybin += nygroup;
         }
         oldxbin += nxgroup;
      }
 
      // compute new underflow/overflows for the 8 vertices
      for (Int_t xover = 0; xover <= 1; xover++) {
         for (Int_t yover = 0; yover <= 1; yover++) {
            for (Int_t zover = 0; zover <= 1; zover++) {
               binContent = 0;
               binSumw2 = 0;
               // make loop in case of only underflow/overflow
               for (xbin = xover*oldxbin; xbin <= xover*(nxbins+1); xbin++) {
                  for (ybin = yover*oldybin; ybin <= yover*(nybins+1); ybin++) {
                     for (zbin = zover*oldzbin; zbin <= zover*(nzbins+1); zbin++) {
                        bin = GetBin(xbin,ybin,zbin);
                        binContent += oldBins[bin];
                        if (oldSumw2) binSumw2 += oldSumw2[bin];
                     }
                  }
               }
               Int_t binNew = hnew->GetBin( xover *(newxbins+1),
                                           yover*(newybins+1), zover*(newzbins+1) );
               hnew->SetBinContent(binNew,binContent);
               if (oldSumw2) hnew->fSumw2.fArray[binNew] = binSumw2;
            }
         }
      }
 
      Double_t binContent0, binContent2, binContent3, binContent4;
      Double_t binError0, binError2, binError3, binError4;
      Int_t oldxbin2, oldybin2, oldzbin2;
      Int_t ufbin, ofbin, ofbin2, ofbin3, ofbin4;
 
      //  recompute under/overflow contents in y for the new  x and z bins
      oldxbin2 = 1;
      oldybin2 = 1;
      oldzbin2 = 1;
      for (xbin = 1; xbin<=newxbins; xbin++) {
         oldzbin2 = 1;
         for (zbin = 1; zbin<=newzbins; zbin++) {
            binContent0 = binContent2 = 0;
            binError0 = binError2 = 0;
            for (i=0; i<nxgroup; i++) {
               if (oldxbin2+i > nxbins) break;
               for (k=0; k<nzgroup; k++) {
                  if (oldzbin2+k > nzbins) break;
                  //old underflow bin (in y)
                  ufbin = oldxbin2 + i + (nxbins+2)*(nybins+2)*(oldzbin2+k);
                  binContent0 += oldBins[ufbin];
                  if (oldSumw2) binError0 += oldSumw2[ufbin];
                  for (ybin = oldybin; ybin <= nybins + 1; ybin++) {
                     //old overflow bin (in y)
                     ofbin = ufbin + ybin*(nxbins+2);
                     binContent2 += oldBins[ofbin];
                     if (oldSumw2) binError2 += oldSumw2[ofbin];
                  }
               }
            }
            hnew->SetBinContent(xbin,0,zbin,binContent0);
            hnew->SetBinContent(xbin,newybins+1,zbin,binContent2);
            if (oldSumw2) {
               hnew->SetBinError(xbin,0,zbin,TMath::Sqrt(binError0));
               hnew->SetBinError(xbin,newybins+1,zbin,TMath::Sqrt(binError2) );
            }
            oldzbin2 += nzgroup;
         }
         oldxbin2 += nxgroup;
      }
 
      //  recompute under/overflow contents in x for the new  y and z bins
      oldxbin2 = 1;
      oldybin2 = 1;
      oldzbin2 = 1;
      for (ybin = 1; ybin<=newybins; ybin++) {
         oldzbin2 = 1;
         for (zbin = 1; zbin<=newzbins; zbin++) {
            binContent0 = binContent2 = 0;
            binError0 = binError2 = 0;
            for (j=0; j<nygroup; j++) {
               if (oldybin2+j > nybins) break;
               for (k=0; k<nzgroup; k++) {
                  if (oldzbin2+k > nzbins) break;
                  //old underflow bin (in y)
                  ufbin = (oldybin2 + j)*(nxbins+2) + (nxbins+2)*(nybins+2)*(oldzbin2+k);
                  binContent0 += oldBins[ufbin];
                  if (oldSumw2) binError0 += oldSumw2[ufbin];
                  for (xbin = oldxbin; xbin <= nxbins + 1; xbin++) {
                     //old overflow bin (in x)
                     ofbin = ufbin + xbin;
                     binContent2 += oldBins[ofbin];
                     if (oldSumw2) binError2 += oldSumw2[ofbin];
                  }
               }
            }
            hnew->SetBinContent(0,ybin,zbin,binContent0);
            hnew->SetBinContent(newxbins+1,ybin,zbin,binContent2);
            if (oldSumw2) {
               hnew->SetBinError(0,ybin,zbin,TMath::Sqrt(binError0));
               hnew->SetBinError(newxbins+1,ybin,zbin,TMath::Sqrt(binError2) );
            }
            oldzbin2 += nzgroup;
         }
         oldybin2 += nygroup;
      }
 
      //  recompute under/overflow contents in z for the new  x and y bins
      oldxbin2 = 1;
      oldybin2 = 1;
      oldzbin2 = 1;
      for (xbin = 1; xbin<=newxbins; xbin++) {
         oldybin2 = 1;
         for (ybin = 1; ybin<=newybins; ybin++) {
            binContent0 = binContent2 = 0;
            binError0 = binError2 = 0;
            for (i=0; i<nxgroup; i++) {
               if (oldxbin2+i > nxbins) break;
               for (j=0; j<nygroup; j++) {
                  if (oldybin2+j > nybins) break;
                  //old underflow bin (in z)
                  ufbin = oldxbin2 + i + (nxbins+2)*(oldybin2+j);
                  binContent0 += oldBins[ufbin];
                  if (oldSumw2) binError0 += oldSumw2[ufbin];
                  for (zbin = oldzbin; zbin <= nzbins + 1; zbin++) {
                     //old overflow bin (in z)
                     ofbin = ufbin + (nxbins+2)*(nybins+2)*zbin;
                     binContent2 += oldBins[ofbin];
                     if (oldSumw2) binError2 += oldSumw2[ofbin];
                  }
               }
            }
            hnew->SetBinContent(xbin,ybin,0,binContent0);
            hnew->SetBinContent(xbin,ybin,newzbins+1,binContent2);
            if (oldSumw2) {
               hnew->SetBinError(xbin,ybin,0,TMath::Sqrt(binError0));
               hnew->SetBinError(xbin,ybin,newzbins+1,TMath::Sqrt(binError2) );
            }
            oldybin2 += nygroup;
         }
         oldxbin2 += nxgroup;
      }
 
      //  recompute under/overflow contents in y, z for the new  x
      oldxbin2 = 1;
      oldybin2 = 1;
      oldzbin2 = 1;
      for (xbin = 1; xbin<=newxbins; xbin++) {
         binContent0 = 0;
         binContent2 = 0;
         binContent3 = 0;
         binContent4 = 0;
         binError0 = 0;
         binError2 = 0;
         binError3 = 0;
         binError4 = 0;
         for (i=0; i<nxgroup; i++) {
            if (oldxbin2+i > nxbins) break;
            ufbin = oldxbin2 + i; //
            binContent0 += oldBins[ufbin];
            if (oldSumw2) binError0 += oldSumw2[ufbin];
            for (ybin = oldybin; ybin <= nybins + 1; ybin++) {
               ofbin3 =  ufbin+ybin*(nxbins+2);
               binContent3 += oldBins[ ofbin3 ];
               if (oldSumw2)  binError3 += oldSumw2[ofbin3];
               for (zbin = oldzbin; zbin <= nzbins + 1; zbin++) {
                  //old overflow bin (in z)
                  ofbin4 =   oldxbin2 + i + ybin*(nxbins+2) + (nxbins+2)*(nybins+2)*zbin;
                  binContent4 += oldBins[ofbin4];
                  if (oldSumw2) binError4 += oldSumw2[ofbin4];
               }
            }
            for (zbin = oldzbin; zbin <= nzbins + 1; zbin++) {
               ofbin2 =  ufbin+zbin*(nxbins+2)*(nybins+2);
               binContent2 += oldBins[ ofbin2 ];
               if (oldSumw2)  binError2 += oldSumw2[ofbin2];
            }
         }
         hnew->SetBinContent(xbin,0,0,binContent0);
         hnew->SetBinContent(xbin,0,newzbins+1,binContent2);
         hnew->SetBinContent(xbin,newybins+1,0,binContent3);
         hnew->SetBinContent(xbin,newybins+1,newzbins+1,binContent4);
         if (oldSumw2) {
            hnew->SetBinError(xbin,0,0,TMath::Sqrt(binError0));
            hnew->SetBinError(xbin,0,newzbins+1,TMath::Sqrt(binError2) );
            hnew->SetBinError(xbin,newybins+1,0,TMath::Sqrt(binError3) );
            hnew->SetBinError(xbin,newybins+1,newzbins+1,TMath::Sqrt(binError4) );
         }
         oldxbin2 += nxgroup;
      }
 
      //  recompute under/overflow contents in x, y for the new z
      oldxbin2 = 1;
      oldybin2 = 1;
      oldzbin2 = 1;
      for (zbin = 1; zbin<=newzbins; zbin++) {
         binContent0 = 0;
         binContent2 = 0;
         binContent3 = 0;
         binContent4 = 0;
         binError0 = 0;
         binError2 = 0;
         binError3 = 0;
         binError4 = 0;
         for (i=0; i<nzgroup; i++) {
            if (oldzbin2+i > nzbins) break;
            ufbin = (oldzbin2 + i)*(nxbins+2)*(nybins+2); //
            binContent0 += oldBins[ufbin];
            if (oldSumw2) binError0 += oldSumw2[ufbin];
            for (ybin = oldybin; ybin <= nybins + 1; ybin++) {
               ofbin3 =  ufbin+ybin*(nxbins+2);
               binContent3 += oldBins[ ofbin3 ];
               if (oldSumw2)  binError3 += oldSumw2[ofbin3];
               for (xbin = oldxbin; xbin <= nxbins + 1; xbin++) {
                  //old overflow bin (in z)
                  ofbin4 = ufbin + xbin + ybin*(nxbins+2);
                  binContent4 += oldBins[ofbin4];
                  if (oldSumw2) binError4 += oldSumw2[ofbin4];
               }
            }
            for (xbin = oldxbin; xbin <= nxbins + 1; xbin++) {
               ofbin2 =  xbin +(oldzbin2+i)*(nxbins+2)*(nybins+2);
               binContent2 += oldBins[ ofbin2 ];
               if (oldSumw2)  binError2 += oldSumw2[ofbin2];
            }
         }
         hnew->SetBinContent(0,0,zbin,binContent0);
         hnew->SetBinContent(0,newybins+1,zbin,binContent3);
         hnew->SetBinContent(newxbins+1,0,zbin,binContent2);
         hnew->SetBinContent(newxbins+1,newybins+1,zbin,binContent4);
         if (oldSumw2) {
            hnew->SetBinError(0,0,zbin,TMath::Sqrt(binError0));
            hnew->SetBinError(0,newybins+1,zbin,TMath::Sqrt(binError3) );
            hnew->SetBinError(newxbins+1,0,zbin,TMath::Sqrt(binError2) );
            hnew->SetBinError(newxbins+1,newybins+1,zbin,TMath::Sqrt(binError4) );
         }
         oldzbin2 += nzgroup;
      }
 
      //  recompute under/overflow contents in x, z for the new  y
      oldxbin2 = 1;
      oldybin2 = 1;
      oldzbin2 = 1;
      for (ybin = 1; ybin<=newybins; ybin++) {
         binContent0 = 0;
         binContent2 = 0;
         binContent3 = 0;
         binContent4 = 0;
         binError0 = 0;
         binError2 = 0;
         binError3 = 0;
         binError4 = 0;
         for (i=0; i<nygroup; i++) {
            if (oldybin2+i > nybins) break;
            ufbin = (oldybin2 + i)*(nxbins+2); //
            binContent0 += oldBins[ufbin];
            if (oldSumw2) binError0 += oldSumw2[ufbin];
            for (xbin = oldxbin; xbin <= nxbins + 1; xbin++) {
               ofbin3 =  ufbin+xbin;
               binContent3 += oldBins[ ofbin3 ];
               if (oldSumw2)  binError3 += oldSumw2[ofbin3];
               for (zbin = oldzbin; zbin <= nzbins + 1; zbin++) {
                  //old overflow bin (in z)
                  ofbin4 = xbin + (nxbins+2)*(nybins+2)*zbin+(oldybin2+i)*(nxbins+2);
                  binContent4 += oldBins[ofbin4];
                  if (oldSumw2) binError4 += oldSumw2[ofbin4];
               }
            }
            for (zbin = oldzbin; zbin <= nzbins + 1; zbin++) {
               ofbin2 =  (oldybin2+i)*(nxbins+2)+zbin*(nxbins+2)*(nybins+2);
               binContent2 += oldBins[ ofbin2 ];
               if (oldSumw2)  binError2 += oldSumw2[ofbin2];
            }
         }
         hnew->SetBinContent(0,ybin,0,binContent0);
         hnew->SetBinContent(0,ybin,newzbins+1,binContent2);
         hnew->SetBinContent(newxbins+1,ybin,0,binContent3);
         hnew->SetBinContent(newxbins+1,ybin,newzbins+1,binContent4);
         if (oldSumw2) {
            hnew->SetBinError(0,ybin,0,TMath::Sqrt(binError0));
            hnew->SetBinError(0,ybin,newzbins+1,TMath::Sqrt(binError2) );
            hnew->SetBinError(newxbins+1,ybin,0,TMath::Sqrt(binError3) );
            hnew->SetBinError(newxbins+1,ybin,newzbins+1,TMath::Sqrt(binError4) );
         }
         oldybin2 += nygroup;
      }
   }
 
   // Restore x axis attributes
   fXaxis.SetNdivisions(nXdivisions);
   fXaxis.SetAxisColor(xAxisColor);
   fXaxis.SetLabelColor(xLabelColor);
   fXaxis.SetLabelFont(xLabelFont);
   fXaxis.SetLabelOffset(xLabelOffset);
   fXaxis.SetLabelSize(xLabelSize);
   fXaxis.SetTickLength(xTickLength);
   fXaxis.SetTitleOffset(xTitleOffset);
   fXaxis.SetTitleSize(xTitleSize);
   fXaxis.SetTitleColor(xTitleColor);
   fXaxis.SetTitleFont(xTitleFont);
   // Restore y axis attributes
   fYaxis.SetNdivisions(nYdivisions);
   fYaxis.SetAxisColor(yAxisColor);
   fYaxis.SetLabelColor(yLabelColor);
   fYaxis.SetLabelFont(yLabelFont);
   fYaxis.SetLabelOffset(yLabelOffset);
   fYaxis.SetLabelSize(yLabelSize);
   fYaxis.SetTickLength(yTickLength);
   fYaxis.SetTitleOffset(yTitleOffset);
   fYaxis.SetTitleSize(yTitleSize);
   fYaxis.SetTitleColor(yTitleColor);
   fYaxis.SetTitleFont(yTitleFont);
   // Restore z axis attributes
   fZaxis.SetNdivisions(nZdivisions);
   fZaxis.SetAxisColor(zAxisColor);
   fZaxis.SetLabelColor(zLabelColor);
   fZaxis.SetLabelFont(zLabelFont);
   fZaxis.SetLabelOffset(zLabelOffset);
   fZaxis.SetLabelSize(zLabelSize);
   fZaxis.SetTickLength(zTickLength);
   fZaxis.SetTitleOffset(zTitleOffset);
   fZaxis.SetTitleSize(zTitleSize);
   fZaxis.SetTitleColor(zTitleColor);
   fZaxis.SetTitleFont(zTitleFont);
 
   //restore statistics and entries  modified by SetBinContent
   hnew->SetEntries(entries);
   if (!resetStat) hnew->PutStats(stat);
 
   delete [] oldBins;
   if (oldSumw2) delete [] oldSumw2;
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this histogram: contents, errors, etc.
 
void TH3::Reset(Option_t *option)
{
   TH1::Reset(option);
   TString opt = option;
   opt.ToUpper();
   if (opt.Contains("ICE") && !opt.Contains("S")) return;
   fTsumwy  = 0;
   fTsumwy2 = 0;
   fTsumwxy = 0;
   fTsumwz  = 0;
   fTsumwz2 = 0;
   fTsumwxz = 0;
   fTsumwyz = 0;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set bin content.
 
void TH3::SetBinContent(Int_t bin, Double_t content)
{
   fEntries++;
   fTsumw = 0;
   if (bin < 0) return;
   if (bin >= fNcells) return;
   UpdateBinContent(bin, content);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Stream an object of class TH3.
 
void TH3::Streamer(TBuffer &R__b)
{
   if (R__b.IsReading()) {
      UInt_t R__s, R__c;
      Version_t R__v = R__b.ReadVersion(&R__s, &R__c);
      if (R__v > 2) {
         R__b.ReadClassBuffer(TH3::Class(), this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      TH1::Streamer(R__b);
      TAtt3D::Streamer(R__b);
      R__b.CheckByteCount(R__s, R__c, TH3::IsA());
      //====end of old versions
 
   } else {
      R__b.WriteClassBuffer(TH3::Class(),this);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// static method performing the projection to 1D histogram
 
TH1D *TH3::DoProject1D(const TH3 &h, const char *name, const char *title, const TAxis *projX, bool computeErrors,
                       bool originalRange, bool useUF, bool useOF, bool useWidth)
{
   return h.DoProject1D(name, title, projX, nullptr, nullptr, computeErrors, originalRange, useUF, useOF, useWidth);
}
 
////////////////////////////////////////////////////////////////////////////////
/// static method performing the projection to 2D histogram
 
TH2D *TH3::DoProject2D(const TH3 &h, const char *name, const char *title, const TAxis *projX, const TAxis *projY,
                       bool computeErrors, bool originalRange, bool useUF, bool useOF, bool useWidth)
{
   return h.DoProject2D(name, title, projX, projY, computeErrors, originalRange, useUF, useOF, useWidth);
}
 
//______________________________________________________________________________
//                     TH3C methods
//  TH3C a 3-D histogram with one byte per cell (char)
//______________________________________________________________________________
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
 
TH3C::TH3C()
{
   SetBinsLength(27);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TH3C::~TH3C()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for fix bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3C::TH3C(const char *name,const char *title,Int_t nbinsx,Double_t xlow,Double_t xup
           ,Int_t nbinsy,Double_t ylow,Double_t yup
           ,Int_t nbinsz,Double_t zlow,Double_t zup)
           :TH3(name,title,nbinsx,xlow,xup,nbinsy,ylow,yup,nbinsz,zlow,zup)
{
   TArrayC::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
 
   if (xlow >= xup || ylow >= yup || zlow >= zup) SetBuffer(fgBufferSize);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms.
/// (see TH3::TH3 for explanation of parameters)
 
TH3C::TH3C(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins
           ,Int_t nbinsy,const Float_t *ybins
           ,Int_t nbinsz,const Float_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayC::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms.
/// (see TH3::TH3 for explanation of parameters)
 
TH3C::TH3C(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins
           ,Int_t nbinsy,const Double_t *ybins
           ,Int_t nbinsz,const Double_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayC::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor.
/// The list of functions is not copied. (Use Clone() if needed)
 
TH3C::TH3C(const TH3C &h3c) : TH3(), TArrayC()
{
   h3c.TH3C::Copy(*this);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by 1.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3C::AddBinContent(Int_t bin)
{
   if (fArray[bin] < 127) fArray[bin]++;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by w.
/// \warning The value of w is cast to `Int_t` before being added.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3C::AddBinContent(Int_t bin, Double_t w)
{
   Int_t newval = fArray[bin] + Int_t(w);
   if (newval > -128 && newval < 128) {fArray[bin] = Char_t(newval); return;}
   if (newval < -127) fArray[bin] = -127;
   if (newval >  127) fArray[bin] =  127;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this 3-D histogram structure to newth3.
 
void TH3C::Copy(TObject &newth3) const
{
   TH3::Copy(newth3);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this histogram: contents, errors, etc.
 
void TH3C::Reset(Option_t *option)
{
   TH3::Reset(option);
   TArrayC::Reset();
   // should also reset statistics once statistics are implemented for TH3
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set total number of bins including under/overflow
/// Reallocate bin contents array
 
void TH3C::SetBinsLength(Int_t n)
{
   if (n < 0) n = (fXaxis.GetNbins()+2)*(fYaxis.GetNbins()+2)*(fZaxis.GetNbins()+2);
   fNcells = n;
   TArrayC::Set(n);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// When the mouse is moved in a pad containing a 3-d view of this histogram
/// a second canvas shows a projection type given as option.
/// To stop the generation of the projections, delete the canvas
/// containing the projection.
/// option may contain a combination of the characters x,y,z,e
/// option = "x" return the x projection into a TH1D histogram
/// option = "y" return the y projection into a TH1D histogram
/// option = "z" return the z projection into a TH1D histogram
/// option = "xy" return the x versus y projection into a TH2D histogram
/// option = "yx" return the y versus x projection into a TH2D histogram
/// option = "xz" return the x versus z projection into a TH2D histogram
/// option = "zx" return the z versus x projection into a TH2D histogram
/// option = "yz" return the y versus z projection into a TH2D histogram
/// option = "zy" return the z versus y projection into a TH2D histogram
/// option can also include the drawing option for the projection, eg to draw
/// the xy projection using the draw option "box" do
///   myhist.SetShowProjection("xy box");
/// This function is typically called from the context menu.
/// NB: the notation "a vs b" means "a" vertical and "b" horizontal
 
void TH3::SetShowProjection(const char *option,Int_t nbins)
{
   GetPainter();
 
   if (fPainter) fPainter->SetShowProjection(option,nbins);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Stream an object of class TH3C.
 
void TH3C::Streamer(TBuffer &R__b)
{
   if (R__b.IsReading()) {
      UInt_t R__s, R__c;
      if (R__b.GetParent() && R__b.GetVersionOwner() < 22300) return;
      Version_t R__v = R__b.ReadVersion(&R__s, &R__c);
      if (R__v > 2) {
         R__b.ReadClassBuffer(TH3C::Class(), this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      if (R__v < 2) {
         R__b.ReadVersion();
         TH1::Streamer(R__b);
         TArrayC::Streamer(R__b);
         R__b.ReadVersion(&R__s, &R__c);
         TAtt3D::Streamer(R__b);
      } else {
         TH3::Streamer(R__b);
         TArrayC::Streamer(R__b);
         R__b.CheckByteCount(R__s, R__c, TH3C::IsA());
      }
      //====end of old versions
 
   } else {
      R__b.WriteClassBuffer(TH3C::Class(),this);
   }
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator =
 
TH3C& TH3C::operator=(const TH3C &h3c)
{
   if (this != &h3c)
      h3c.TH3C::Copy(*this);
   return *this;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3C operator*(Float_t c1, TH3C const &h3c)
{
   TH3C hnew = h3c;
   hnew.Scale(c1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator +
 
TH3C operator+(TH3C const &h1, TH3C const &h2)
{
   TH3C hnew = h1;
   hnew.Add(&h2,1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator -
 
TH3C operator-(TH3C const &h1, TH3C const &h2)
{
   TH3C hnew = h1;
   hnew.Add(&h2,-1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3C operator*(TH3C const &h1, TH3C const &h2)
{
   TH3C hnew = h1;
   hnew.Multiply(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator /
 
TH3C operator/(TH3C const &h1, TH3C const &h2)
{
   TH3C hnew = h1;
   hnew.Divide(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
//______________________________________________________________________________
//                     TH3S methods
//  TH3S a 3-D histogram with two bytes per cell (short integer)
//______________________________________________________________________________
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
 
TH3S::TH3S()
{
   SetBinsLength(27);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TH3S::~TH3S()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for fix bin size 3-D histograms.
/// (see TH3::TH3 for explanation of parameters)
 
TH3S::TH3S(const char *name,const char *title,Int_t nbinsx,Double_t xlow,Double_t xup
           ,Int_t nbinsy,Double_t ylow,Double_t yup
           ,Int_t nbinsz,Double_t zlow,Double_t zup)
           :TH3(name,title,nbinsx,xlow,xup,nbinsy,ylow,yup,nbinsz,zlow,zup)
{
   TH3S::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
 
   if (xlow >= xup || ylow >= yup || zlow >= zup) SetBuffer(fgBufferSize);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms.
/// (see TH3::TH3 for explanation of parameters)
 
TH3S::TH3S(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins
           ,Int_t nbinsy,const Float_t *ybins
           ,Int_t nbinsz,const Float_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TH3S::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms.
/// (see TH3::TH3 for explanation of parameters)
 
TH3S::TH3S(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins
           ,Int_t nbinsy,const Double_t *ybins
           ,Int_t nbinsz,const Double_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TH3S::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy Constructor.
/// The list of functions is not copied. (Use Clone() if needed)
 
TH3S::TH3S(const TH3S &h3s) : TH3(), TArrayS()
{
   h3s.TH3S::Copy(*this);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by 1.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3S::AddBinContent(Int_t bin)
{
   if (fArray[bin] < 32767) fArray[bin]++;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by w.
/// \warning The value of w is cast to `Int_t` before being added.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3S::AddBinContent(Int_t bin, Double_t w)
{
   Int_t newval = fArray[bin] + Int_t(w);
   if (newval > -32768 && newval < 32768) {fArray[bin] = Short_t(newval); return;}
   if (newval < -32767) fArray[bin] = -32767;
   if (newval >  32767) fArray[bin] =  32767;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this 3-D histogram structure to newth3.
 
void TH3S::Copy(TObject &newth3) const
{
   TH3::Copy(newth3);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this histogram: contents, errors, etc.
 
void TH3S::Reset(Option_t *option)
{
   TH3::Reset(option);
   TArrayS::Reset();
   // should also reset statistics once statistics are implemented for TH3
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set total number of bins including under/overflow
/// Reallocate bin contents array
 
void TH3S::SetBinsLength(Int_t n)
{
   if (n < 0) n = (fXaxis.GetNbins()+2)*(fYaxis.GetNbins()+2)*(fZaxis.GetNbins()+2);
   fNcells = n;
   TArrayS::Set(n);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Stream an object of class TH3S.
 
void TH3S::Streamer(TBuffer &R__b)
{
   if (R__b.IsReading()) {
      UInt_t R__s, R__c;
      if (R__b.GetParent() && R__b.GetVersionOwner() < 22300) return;
      Version_t R__v = R__b.ReadVersion(&R__s, &R__c);
      if (R__v > 2) {
         R__b.ReadClassBuffer(TH3S::Class(), this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      if (R__v < 2) {
         R__b.ReadVersion();
         TH1::Streamer(R__b);
         TArrayS::Streamer(R__b);
         R__b.ReadVersion(&R__s, &R__c);
         TAtt3D::Streamer(R__b);
      } else {
         TH3::Streamer(R__b);
         TArrayS::Streamer(R__b);
         R__b.CheckByteCount(R__s, R__c, TH3S::IsA());
      }
      //====end of old versions
 
   } else {
      R__b.WriteClassBuffer(TH3S::Class(),this);
   }
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator =
 
TH3S& TH3S::operator=(const TH3S &h3s)
{
   if (this != &h3s)
      h3s.TH3S::Copy(*this);
   return *this;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3S operator*(Float_t c1, TH3S const &h3s)
{
   TH3S hnew = h3s;
   hnew.Scale(c1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator +
 
TH3S operator+(TH3S const &h1, TH3S const &h2)
{
   TH3S hnew = h1;
   hnew.Add(&h2,1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator -
 
TH3S operator-(TH3S const &h1, TH3S const &h2)
{
   TH3S hnew = h1;
   hnew.Add(&h2,-1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3S operator*(TH3S const &h1, TH3S const &h2)
{
   TH3S hnew = h1;
   hnew.Multiply(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator /
 
TH3S operator/(TH3S const &h1, TH3S const &h2)
{
   TH3S hnew = h1;
   hnew.Divide(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
//______________________________________________________________________________
//                     TH3I methods
//  TH3I a 3-D histogram with four bytes per cell (32 bit integer)
//______________________________________________________________________________
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
 
TH3I::TH3I()
{
   SetBinsLength(27);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TH3I::~TH3I()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for fix bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3I::TH3I(const char *name,const char *title,Int_t nbinsx,Double_t xlow,Double_t xup
           ,Int_t nbinsy,Double_t ylow,Double_t yup
           ,Int_t nbinsz,Double_t zlow,Double_t zup)
           :TH3(name,title,nbinsx,xlow,xup,nbinsy,ylow,yup,nbinsz,zlow,zup)
{
   TH3I::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
 
   if (xlow >= xup || ylow >= yup || zlow >= zup) SetBuffer(fgBufferSize);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3I::TH3I(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins
           ,Int_t nbinsy,const Float_t *ybins
           ,Int_t nbinsz,const Float_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayI::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3I::TH3I(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins
           ,Int_t nbinsy,const Double_t *ybins
           ,Int_t nbinsz,const Double_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayI::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor.
/// The list of functions is not copied. (Use Clone() if needed)
 
TH3I::TH3I(const TH3I &h3i) : TH3(), TArrayI()
{
   h3i.TH3I::Copy(*this);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by 1.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3I::AddBinContent(Int_t bin)
{
   if (fArray[bin] < INT_MAX) fArray[bin]++;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by w.
/// \warning The value of w is cast to `Long64_t` before being added.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3I::AddBinContent(Int_t bin, Double_t w)
{
   Long64_t newval = fArray[bin] + Long64_t(w);
   if (newval > -INT_MAX && newval < INT_MAX) {fArray[bin] = Int_t(newval); return;}
   if (newval < -INT_MAX) fArray[bin] = -INT_MAX;
   if (newval >  INT_MAX) fArray[bin] =  INT_MAX;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this 3-D histogram structure to newth3.
 
void TH3I::Copy(TObject &newth3) const
{
   TH3::Copy(newth3);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this histogram: contents, errors, etc.
 
void TH3I::Reset(Option_t *option)
{
   TH3::Reset(option);
   TArrayI::Reset();
   // should also reset statistics once statistics are implemented for TH3
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set total number of bins including under/overflow
/// Reallocate bin contents array
 
void TH3I::SetBinsLength(Int_t n)
{
   if (n < 0) n = (fXaxis.GetNbins()+2)*(fYaxis.GetNbins()+2)*(fZaxis.GetNbins()+2);
   fNcells = n;
   TArrayI::Set(n);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator =
 
TH3I& TH3I::operator=(const TH3I &h3i)
{
   if (this != &h3i)
      h3i.TH3I::Copy(*this);
   return *this;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3I operator*(Float_t c1, TH3I const &h3i)
{
   TH3I hnew = h3i;
   hnew.Scale(c1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator +
 
TH3I operator+(TH3I const &h1, TH3I const &h2)
{
   TH3I hnew = h1;
   hnew.Add(&h2,1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator _
 
TH3I operator-(TH3I const &h1, TH3I const &h2)
{
   TH3I hnew = h1;
   hnew.Add(&h2,-1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3I operator*(TH3I const &h1, TH3I const &h2)
{
   TH3I hnew = h1;
   hnew.Multiply(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator /
 
TH3I operator/(TH3I const &h1, TH3I const &h2)
{
   TH3I hnew = h1;
   hnew.Divide(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
//______________________________________________________________________________
//                     TH3L methods
//  TH3L a 3-D histogram with eight bytes per cell (64 bit integer)
//______________________________________________________________________________
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
 
TH3L::TH3L()
{
   SetBinsLength(27);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TH3L::~TH3L()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for fix bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3L::TH3L(const char *name,const char *title,Int_t nbinsx,Double_t xlow,Double_t xup
           ,Int_t nbinsy,Double_t ylow,Double_t yup
           ,Int_t nbinsz,Double_t zlow,Double_t zup)
   :TH3(name,title,nbinsx,xlow,xup,nbinsy,ylow,yup,nbinsz,zlow,zup)
{
   TH3L::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
 
   if (xlow >= xup || ylow >= yup || zlow >= zup) SetBuffer(fgBufferSize);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3L::TH3L(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins
           ,Int_t nbinsy,const Float_t *ybins
           ,Int_t nbinsz,const Float_t *zbins)
   :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayL64::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3L::TH3L(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins
           ,Int_t nbinsy,const Double_t *ybins
           ,Int_t nbinsz,const Double_t *zbins)
   :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayL64::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor.
/// The list of functions is not copied. (Use Clone() if needed)
 
TH3L::TH3L(const TH3L &h3l) : TH3(), TArrayL64()
{
   h3l.TH3L::Copy(*this);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by 1.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3L::AddBinContent(Int_t bin)
{
   if (fArray[bin] < LLONG_MAX) fArray[bin]++;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Increment bin content by w.
/// \warning The value of w is cast to `Long64_t` before being added.
/// Passing an out-of-range bin leads to undefined behavior
 
void TH3L::AddBinContent(Int_t bin, Double_t w)
{
   Long64_t newval = fArray[bin] + Long64_t(w);
   if (newval > -LLONG_MAX && newval < LLONG_MAX) {fArray[bin] = newval; return;}
   if (newval < -LLONG_MAX) fArray[bin] = -LLONG_MAX;
   if (newval >  LLONG_MAX) fArray[bin] =  LLONG_MAX;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this 3-D histogram structure to newth3.
 
void TH3L::Copy(TObject &newth3) const
{
   TH3::Copy(newth3);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this histogram: contents, errors, etc.
 
void TH3L::Reset(Option_t *option)
{
   TH3::Reset(option);
   TArrayL64::Reset();
   // should also reset statistics once statistics are implemented for TH3
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set total number of bins including under/overflow
/// Reallocate bin contents array
 
void TH3L::SetBinsLength(Int_t n)
{
   if (n < 0) n = (fXaxis.GetNbins()+2)*(fYaxis.GetNbins()+2)*(fZaxis.GetNbins()+2);
   fNcells = n;
   TArrayL64::Set(n);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator =
 
TH3L& TH3L::operator=(const TH3L &h3l)
{
   if (this != &h3l)
      h3l.TH3L::Copy(*this);
   return *this;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3L operator*(Float_t c1, TH3L const &h3l)
{
   TH3L hnew = h3l;
   hnew.Scale(c1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator +
 
TH3L operator+(TH3L const &h1, TH3L const &h2)
{
   TH3L hnew = h1;
   hnew.Add(&h2,1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator _
 
TH3L operator-(TH3L const &h1, TH3L const &h2)
{
   TH3L hnew = h1;
   hnew.Add(&h2,-1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3L operator*(TH3L const &h1, TH3L const &h2)
{
   TH3L hnew = h1;
   hnew.Multiply(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator /
 
TH3L operator/(TH3L const &h1, TH3L const &h2)
{
   TH3L hnew = h1;
   hnew.Divide(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
//______________________________________________________________________________
//                     TH3F methods
//  TH3F a 3-D histogram with four bytes per cell (float). Maximum precision 7 digits, maximum integer bin content = +/-16777216
//______________________________________________________________________________
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
 
TH3F::TH3F()
{
   SetBinsLength(27);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TH3F::~TH3F()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for fix bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3F::TH3F(const char *name,const char *title,Int_t nbinsx,Double_t xlow,Double_t xup
           ,Int_t nbinsy,Double_t ylow,Double_t yup
           ,Int_t nbinsz,Double_t zlow,Double_t zup)
           :TH3(name,title,nbinsx,xlow,xup,nbinsy,ylow,yup,nbinsz,zlow,zup)
{
   TArrayF::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
 
   if (xlow >= xup || ylow >= yup || zlow >= zup) SetBuffer(fgBufferSize);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3F::TH3F(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins
           ,Int_t nbinsy,const Float_t *ybins
           ,Int_t nbinsz,const Float_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayF::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3F::TH3F(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins
           ,Int_t nbinsy,const Double_t *ybins
           ,Int_t nbinsz,const Double_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayF::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor.
/// The list of functions is not copied. (Use Clone() if needed)
 
TH3F::TH3F(const TH3F &h3f) : TH3(), TArrayF()
{
   h3f.TH3F::Copy(*this);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this 3-D histogram structure to newth3.
 
void TH3F::Copy(TObject &newth3) const
{
   TH3::Copy(newth3);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this histogram: contents, errors, etc.
 
void TH3F::Reset(Option_t *option)
{
   TH3::Reset(option);
   TArrayF::Reset();
   // should also reset statistics once statistics are implemented for TH3
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set total number of bins including under/overflow
/// Reallocate bin contents array
 
void TH3F::SetBinsLength(Int_t n)
{
   if (n < 0) n = (fXaxis.GetNbins()+2)*(fYaxis.GetNbins()+2)*(fZaxis.GetNbins()+2);
   fNcells = n;
   TArrayF::Set(n);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Stream an object of class TH3F.
 
void TH3F::Streamer(TBuffer &R__b)
{
   if (R__b.IsReading()) {
      UInt_t R__s, R__c;
      if (R__b.GetParent() && R__b.GetVersionOwner() < 22300) return;
      Version_t R__v = R__b.ReadVersion(&R__s, &R__c);
      if (R__v > 2) {
         R__b.ReadClassBuffer(TH3F::Class(), this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      if (R__v < 2) {
         R__b.ReadVersion();
         TH1::Streamer(R__b);
         TArrayF::Streamer(R__b);
         R__b.ReadVersion(&R__s, &R__c);
         TAtt3D::Streamer(R__b);
      } else {
         TH3::Streamer(R__b);
         TArrayF::Streamer(R__b);
         R__b.CheckByteCount(R__s, R__c, TH3F::IsA());
      }
      //====end of old versions
 
   } else {
      R__b.WriteClassBuffer(TH3F::Class(),this);
   }
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator =
 
TH3F& TH3F::operator=(const TH3F &h3f)
{
   if (this != &h3f)
      h3f.TH3F::Copy(*this);
   return *this;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3F operator*(Float_t c1, TH3F const &h3f)
{
   TH3F hnew = h3f;
   hnew.Scale(c1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator +
 
TH3F operator+(TH3F const &h1, TH3F const &h2)
{
   TH3F hnew = h1;
   hnew.Add(&h2,1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator -
 
TH3F operator-(TH3F const &h1, TH3F const &h2)
{
   TH3F hnew = h1;
   hnew.Add(&h2,-1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3F operator*(TH3F const &h1, TH3F const &h2)
{
   TH3F hnew = h1;
   hnew.Multiply(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator /
 
TH3F operator/(TH3F const &h1, TH3F const &h2)
{
   TH3F hnew = h1;
   hnew.Divide(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
//______________________________________________________________________________
//                     TH3D methods
//  TH3D a 3-D histogram with eight bytes per cell (double). Maximum precision 14 digits, maximum integer bin content = +/-9007199254740992
//______________________________________________________________________________
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
 
TH3D::TH3D()
{
   SetBinsLength(27);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TH3D::~TH3D()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for fix bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3D::TH3D(const char *name,const char *title,Int_t nbinsx,Double_t xlow,Double_t xup
           ,Int_t nbinsy,Double_t ylow,Double_t yup
           ,Int_t nbinsz,Double_t zlow,Double_t zup)
           :TH3(name,title,nbinsx,xlow,xup,nbinsy,ylow,yup,nbinsz,zlow,zup)
{
   TArrayD::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
 
   if (xlow >= xup || ylow >= yup || zlow >= zup) SetBuffer(fgBufferSize);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3D::TH3D(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins
           ,Int_t nbinsy,const Float_t *ybins
           ,Int_t nbinsz,const Float_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayD::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for variable bin size 3-D histograms
/// (see TH3::TH3 for explanation of parameters)
 
TH3D::TH3D(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins
           ,Int_t nbinsy,const Double_t *ybins
           ,Int_t nbinsz,const Double_t *zbins)
           :TH3(name,title,nbinsx,xbins,nbinsy,ybins,nbinsz,zbins)
{
   TArrayD::Set(fNcells);
   if (fgDefaultSumw2) Sumw2();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor.
/// The list of functions is not copied. (Use Clone() if needed)
 
TH3D::TH3D(const TH3D &h3d) : TH3(), TArrayD()
{
   // intentially call virtual Copy method to warn if TProfile3D is copied
   h3d.Copy(*this);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this 3-D histogram structure to newth3.
 
void TH3D::Copy(TObject &newth3) const
{
   TH3::Copy(newth3);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this histogram: contents, errors, etc.
 
void TH3D::Reset(Option_t *option)
{
   TH3::Reset(option);
   TArrayD::Reset();
   // should also reset statistics once statistics are implemented for TH3
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set total number of bins including under/overflow
/// Reallocate bin contents array
 
void TH3D::SetBinsLength(Int_t n)
{
   if (n < 0) n = (fXaxis.GetNbins()+2)*(fYaxis.GetNbins()+2)*(fZaxis.GetNbins()+2);
   fNcells = n;
   TArrayD::Set(n);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Stream an object of class TH3D.
 
void TH3D::Streamer(TBuffer &R__b)
{
   if (R__b.IsReading()) {
      UInt_t R__s, R__c;
      if (R__b.GetParent() && R__b.GetVersionOwner() < 22300) return;
      Version_t R__v = R__b.ReadVersion(&R__s, &R__c);
      if (R__v > 2) {
         R__b.ReadClassBuffer(TH3D::Class(), this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      if (R__v < 2) {
         R__b.ReadVersion();
         TH1::Streamer(R__b);
         TArrayD::Streamer(R__b);
         R__b.ReadVersion(&R__s, &R__c);
         TAtt3D::Streamer(R__b);
      } else {
         TH3::Streamer(R__b);
         TArrayD::Streamer(R__b);
         R__b.CheckByteCount(R__s, R__c, TH3D::IsA());
      }
      //====end of old versions
 
   } else {
      R__b.WriteClassBuffer(TH3D::Class(),this);
   }
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator =
 
TH3D& TH3D::operator=(const TH3D &h3d)
{
   // intentially call virtual Copy method to warn if TProfile3D is copied
   if (this != &h3d)
      h3d.Copy(*this);
   return *this;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3D operator*(Float_t c1, TH3D const &h3d)
{
   TH3D hnew = h3d;
   hnew.Scale(c1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator +
 
TH3D operator+(TH3D const &h1, TH3D const &h2)
{
   TH3D hnew = h1;
   hnew.Add(&h2,1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator -
 
TH3D operator-(TH3D const &h1, TH3D const &h2)
{
   TH3D hnew = h1;
   hnew.Add(&h2,-1);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator *
 
TH3D operator*(TH3D const &h1, TH3D const &h2)
{
   TH3D hnew = h1;
   hnew.Multiply(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Operator /
 
TH3D operator/(TH3D const &h1, TH3D const &h2)
{
   TH3D hnew = h1;
   hnew.Divide(&h2);
   hnew.SetDirectory(nullptr);
   return hnew;
}
 
////////////////////////////////////////////////////////////////////////////////
///   This function calculates the background spectrum in this histogram.
///   The background is returned as a histogram.
 
TH1 *TH3::ShowBackground3D(Int_t nIterX, Int_t nIterY, Int_t nIterZ, Option_t *option)
{
 
   return (TH1 *)gROOT->ProcessLineFast(
      TString::Format("TSpectrum3::StaticBackground((TH1*)0x%zx,%d,%d,%d,\"%s\")", (size_t)this, nIterX, nIterY, nIterZ, option)
         .Data());
}