RooBinIntegrator.cxx

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/*****************************************************************************
 * Project: RooFit                                                           *
 * Package: RooFitCore                                                       *
 * @(#)root/roofitcore:$Id$
 * Authors:                                                                  *
 *   WV, Wouter Verkerke, UC Santa Barbara, verkerke@slac.stanford.edu       *
 *   DK, David Kirkby,    UC Irvine,         dkirkby@uci.edu                 *
 *                                                                           *
 * Copyright (c) 2000-2005, Regents of the University of California          *
 *                          and Stanford University. All rights reserved.    *
 *                                                                           *
 * Redistribution and use in source and binary forms,                        *
 * with or without modification, are permitted according to the terms        *
 * listed in LICENSE (http://roofit.sourceforge.net/license.txt)             *
 *****************************************************************************/
 
/**
\file RooBinIntegrator.cxx
\class RooBinIntegrator
\ingroup Roofitcore
 
RooBinIntegrator computes the integral over a binned distribution by summing the bin
contents of all bins.
**/
 
#include "RooBinIntegrator.h"
 
#include "RooArgSet.h"
#include "RooRealVar.h"
#include "RooNumber.h"
#include "RooIntegratorBinding.h"
#include "RooNumIntConfig.h"
#include "RooNumIntFactory.h"
#include "RooMsgService.h"
#include "RunContext.h"
#include "RooRealBinding.h"
 
#include "TClass.h"
#include "Math/Util.h"
 
#include <assert.h>
 
 
 
using namespace std;
 
ClassImp(RooBinIntegrator);
;
 
// Register this class with RooNumIntConfig
 
////////////////////////////////////////////////////////////////////////////////
/// Register RooBinIntegrator, is parameters and capabilities with RooNumIntFactory
 
void RooBinIntegrator::registerIntegrator(RooNumIntFactory& fact)
{
  RooRealVar numBins("numBins","Number of bins in range",100) ;
  RooBinIntegrator* proto = new RooBinIntegrator() ;
  fact.storeProtoIntegrator(proto,RooArgSet(numBins)) ;
  RooNumIntConfig::defaultConfig().method1D().setLabel(proto->ClassName()) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Default constructor
 
RooBinIntegrator::RooBinIntegrator() : _numBins(0), _useIntegrandLimits(false), _x(0)
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Construct integrator on given function binding binding
 
RooBinIntegrator::RooBinIntegrator(const RooAbsFunc& function, int numBins):
  RooAbsIntegrator(function)
{
  _useIntegrandLimits= true;
  assert(_function && _function->isValid());
 
  // Allocate coordinate buffer size after number of function dimensions
  _x.resize(_function->getDimension());
  _numBins = numBins;
 
  _xmin.resize(_function->getDimension()) ;
  _xmax.resize(_function->getDimension()) ;
 
  auto realBinding = dynamic_cast<const RooRealBinding*>(_function);
 
  // We could use BatchMode for RooRealBindings as they implement getValues().
  // However, this is not efficient right now, because every time getValue() is
  // called, a new RooFitDriver is created. Needs to be refactored.
 
  //const bool useBatchMode = realBinding;
  const bool useBatchMode = false;
 
  if (useBatchMode) {
    _evalData = std::make_unique<RooBatchCompute::RunContext>();
    _evalDataOrig = std::make_unique<RooBatchCompute::RunContext>();
  }
 
  for (UInt_t i=0 ; i<_function->getDimension() ; i++) {
    _xmin[i]= _function->getMinLimit(i);
    _xmax[i]= _function->getMaxLimit(i);
 
    // Retrieve bin configuration from integrand
    std::unique_ptr<list<double>> tmp{ _function->binBoundaries(i) };
    if (!tmp) {
      oocoutW(nullptr,Integration) << "RooBinIntegrator::RooBinIntegrator WARNING: integrand provide no binning definition observable #"
          << i << " substituting default binning of " << _numBins << " bins" << endl ;
      tmp.reset( new list<double> );
      for (Int_t j=0 ; j<=_numBins ; j++) {
        tmp->push_back(_xmin[i]+j*(_xmax[i]-_xmin[i])/_numBins) ;
      }
    }
    _binb.emplace_back(tmp->begin(), tmp->end());
 
    if (useBatchMode) {
      const std::vector<double>& binb = _binb.back();
      RooSpan<double> binCentres = _evalDataOrig->makeBatch(realBinding->observable(i), binb.size() - 1);
      for (unsigned int ibin = 0; ibin < binb.size() - 1; ++ibin) {
        binCentres[ibin] = (binb[ibin + 1] + binb[ibin]) / 2.;
      }
    }
  }
  checkLimits();
 
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Construct integrator on given function binding binding
 
RooBinIntegrator::RooBinIntegrator(const RooAbsFunc& function, const RooNumIntConfig& config) :
  RooBinIntegrator(function, static_cast<int>(config.getConfigSection("RooBinIntegrator").getRealValue("numBins")))
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Clone integrator with new function binding and configuration. Needed by RooNumIntFactory
 
RooAbsIntegrator* RooBinIntegrator::clone(const RooAbsFunc& function, const RooNumIntConfig& config) const
{
  return new RooBinIntegrator(function,config) ;
}
 
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor
 
RooBinIntegrator::~RooBinIntegrator()
{
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Change our integration limits. Return true if the new limits are
/// ok, or otherwise false. Always returns false and does nothing
/// if this object was constructed to always use our integrand's limits.
 
bool RooBinIntegrator::setLimits(double *xmin, double *xmax)
{
  if(_useIntegrandLimits) {
    oocoutE(nullptr,Integration) << "RooBinIntegrator::setLimits: cannot override integrand's limits" << endl;
    return false;
  }
  _xmin[0]= *xmin;
  _xmax[0]= *xmax;
  return checkLimits();
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Check that our integration range is finite and otherwise return false.
/// Update the limits from the integrand if requested.
 
bool RooBinIntegrator::checkLimits() const
{
  if(_useIntegrandLimits) {
    assert(0 != integrand() && integrand()->isValid());
    _xmin.resize(_function->getDimension()) ;
    _xmax.resize(_function->getDimension()) ;
    for (UInt_t i=0 ; i<_function->getDimension() ; i++) {
      _xmin[i]= integrand()->getMinLimit(i);
      _xmax[i]= integrand()->getMaxLimit(i);
    }
  }
  for (UInt_t i=0 ; i<_function->getDimension() ; i++) {
    if (_xmax[i]<=_xmin[i]) {
      oocoutE(nullptr,Integration) << "RooBinIntegrator::checkLimits: bad range with min >= max (_xmin = " << _xmin[i] << " _xmax = " << _xmax[i] << ")" << endl;
      return false;
    }
    if (RooNumber::isInfinite(_xmin[i]) || RooNumber::isInfinite(_xmax[i])) {
      return false ;
    }
  }
 
  return true;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Calculate numeric integral at given set of function binding parameters.
double RooBinIntegrator::integral(const double *)
{
  assert(isValid());
 
  ROOT::Math::KahanSum<double> sum;
 
  if (_function->getDimension() == 1) {
    const std::vector<double>& binb = _binb[0];
 
    if (_evalData) {
      // Real bindings support batch evaluations. Can fast track now.
      auto realBinding = static_cast<const RooRealBinding*>(integrand());
 
      // Reset computation results to only contain known bin centres, and keep all memory intact:
      _evalData->spans = _evalDataOrig->spans;
      auto results = realBinding->getValuesOfBoundFunction(*_evalData);
      assert(results.size() == binb.size() - 1);
 
      for (unsigned int ibin = 0; ibin < binb.size() - 1; ++ibin) {
        const double width = binb[ibin + 1] - binb[ibin];
        sum += results[ibin] * width;
      }
    } else {
      // Need to use single-value interface
      for (unsigned int ibin=0; ibin < binb.size() - 1; ++ibin) {
        const double xhi = binb[ibin + 1];
        const double xlo = binb[ibin];
        const double xcenter = (xhi+xlo)/2.;
        const double binInt = integrand(xvec(xcenter))*(xhi-xlo) ;
        sum += binInt ;
      }
    }
  } else if (_function->getDimension() == 2) {
    const std::vector<double>& binbx = _binb[0];
    const std::vector<double>& binby = _binb[1];
 
    for (unsigned int ibin1=0; ibin1 < binbx.size() - 1; ++ibin1) {
      const double x1hi = binbx[ibin1 + 1];
      const double x1lo = binbx[ibin1];
      double x1center = (x1hi+x1lo)/2 ;
 
      for (unsigned int ibin2=0; ibin2 < binby.size() - 1; ++ibin2) {
        const double x2hi = binby[ibin2 + 1];
        const double x2lo = binby[ibin2];
        const double x2center = (x2hi+x2lo)/2.;
 
        const double binInt = integrand(xvec(x1center,x2center))*(x1hi-x1lo)*(x2hi-x2lo) ;
        sum += binInt ;
      }
    }
  } else if (_function->getDimension() == 3) {
    const std::vector<double>& binbx = _binb[0];
    const std::vector<double>& binby = _binb[1];
    const std::vector<double>& binbz = _binb[2];
 
    for (unsigned int ibin1=0; ibin1 < binbx.size() - 1; ++ibin1) {
      const double x1hi = binbx[ibin1 + 1];
      const double x1lo = binbx[ibin1];
      double x1center = (x1hi+x1lo)/2 ;
 
      for (unsigned int ibin2=0; ibin2 < binby.size() - 1; ++ibin2) {
        const double x2hi = binby[ibin2 + 1];
        const double x2lo = binby[ibin2];
        const double x2center = (x2hi+x2lo)/2.;
 
        for (unsigned int ibin3=0; ibin3 < binbz.size() - 1; ++ibin3) {
          const double x3hi = binbz[ibin3 + 1];
          const double x3lo = binbz[ibin3];
          const double x3center = (x3hi+x3lo)/2.;
 
          const double binInt = integrand(xvec(x1center,x2center,x3center))*(x1hi-x1lo)*(x2hi-x2lo)*(x3hi-x3lo);
          sum += binInt ;
        }
      }
    }
  }
 
  return sum.Sum();
}