class THStack: public TNamed

 THStack default constructor

 constructor with name and title

 Creates a new THStack from a TH2 or TH3
 It is filled with the 1D histograms from GetProjectionX or GetProjectionY
 for each bin of the histogram. It illustrates the differences and total
 sum along an axis.

 Parameters:
 - hist:  the histogram used for the projections. Can be an object deriving
          from TH2 or TH3.
 - axis:  for TH2: "x" for ProjectionX, "y" for ProjectionY.
          for TH3: see TH3::Project3D.
 - name:  fName is set to name if given, otherwise to histo's name with
          "_stack_<axis>" appended, where <axis> is the value of the
          parameter axis.
 - title: fTitle is set to title if given, otherwise to histo's title
          with ", stack of <axis> projections" appended.
 - firstbin, lastbin:
          for each bin within [firstbin,lastbin] a stack entry is created.
          See TH2::ProjectionX/Y for use overflow bins.
          Defaults to "all bins but under- / overflow"
 - firstbin2, lastbin2:
          Other axis range for TH3::Project3D, defaults to "all bins but
          under- / overflow". Ignored for TH2s
 - proj_option:
          option passed to TH2::ProjectionX/Y and TH3::Project3D (along
          with axis)
 - draw_option:
          option passed to THStack::Add.

 THStack destructor

 THStack copy constructor

 add a new histogram to the list
 Only 1-d and 2-d histograms currently supported.
 A drawing option may be specified

 Browse.

  build sum of all histograms
  Build a separate list fStack containing the running sum of all histograms

 Compute distance from point px,py to each graph

 Draw this multihist with its current attributes.

   Options to draw histograms  are described in THistPainter::Paint
 By default (if option "nostack" is not specified), histograms will be paint
 stacked on top of each other.

    Returns a pointer to the histogram used to draw the axis
    Takes into account the two following cases.
       1- option 'A' was specified in THStack::Draw. Return fHistogram
       2- user had called TPad::DrawFrame. return pointer to hframe histogram

 IMPORTANT NOTES
 - You must call Draw before calling this function. The returned histogram
   depends on the selected Draw options.
 - This function returns a pointer to an intermediate fixed bin size
   histogram used to set the range and for picking.
   You cannot use this histogram to return the bin information.
   You must get a pointer to one of the histograms in the stack,
   the first one, for example.

  returns the maximum of all added histograms
  returns the maximum of all histograms if option "nostack".

  returns the minimum of all added histograms
  returns the minimum of all histograms if option "nostack".

 Return pointer to Stack. Build it if not yet done

 Get x axis of the histogram used to draw the stack.

 IMPORTANT NOTE
  You must call Draw before calling this function. The returned histogram
  depends on the selected Draw options.

 Get x axis of the histogram used to draw the stack.

 IMPORTANT NOTE
  You must call Draw before calling this function. The returned histogram
  depends on the selected Draw options.

 List histograms in the stack

 Merge the THStack in the TList into this stack.
 Returns the total number of histograms in the result or -1 in case of an error.

 invalidate sum of histograms

 paint the list of histograms
 By default, histograms are shown stacked.
    -the first histogram is paint
    -then the sum of the first and second, etc

 If option "nostack" is specified, histograms are all paint in the same pad
 as if the option "same" had been specified.

 if option "pads" is specified, the current pad/canvas is subdivided into
 a number of pads equal to the number of histograms and each histogram
 is paint into a separate pad.

 By default the background of the histograms is erased before drawing the
 histograms. The option "noclear" avoid this behaviour. This is useful
 when drawing a THStack on top of an other plot. If the patterns used to
 draw the histograms in the stack are transparents, then the plot behind
 will be visible.

 See THistPainter::Paint for a list of valid options.

 Print the list of histograms

 Recursively remove object from the list of histograms

 Save primitive as a C++ statement(s) on output stream out

 Set maximum.

 Set minimum.