RooLinTransBinning.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 RooLinTransBinning.cxx
\class RooLinTransBinning
\ingroup Roofitcore
 
Special binning implementation for RooLinearVar
that transforms the binning of the RooLinearVar input variable in the same
way that RooLinearVar does
**/
 
#include "RooLinTransBinning.h"
 
#include <stdexcept>
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor with a given input binning and the slope and offset to be applied to
/// construct the linear transformation
 
RooLinTransBinning::RooLinTransBinning(const RooAbsBinning& input, double slope, double offset, const char* name) :
  RooAbsBinning(name)
{
  updateInput(input,slope,offset) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor
 
RooLinTransBinning::RooLinTransBinning(const RooLinTransBinning &other, const char *name)
   : RooAbsBinning(name), _slope(other._slope), _offset(other._offset), _input(other._input)
{
}
 
////////////////////////////////////////////////////////////////////////////////
 
void RooLinTransBinning::setRange(double /*xlo*/, double /*xhi*/)
{
  // Change limits -- not implemented
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return array of bin boundaries
 
double* RooLinTransBinning::array() const
{
  const int n = numBoundaries();
  // Return array with boundary values
  _array.resize(n);
 
  const double* inputArray = _input->array() ;
 
  if (_slope>0) {
    for (int i=0; i < n; i++) {
      _array[i] = trans(inputArray[i]) ;
    }
  } else {
    for (int i=0; i < n; i++) {
      _array[i] = trans(inputArray[n-i-1]) ;
    }
  }
 
  return _array.data();
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Update the slope and offset parameters and the pointer to the input binning
 
void RooLinTransBinning::updateInput(const RooAbsBinning& input, double slope, double offset)
{
  _input = const_cast<RooAbsBinning*>(&input);
  _slope = slope ;
  _offset = offset ;
}
 
 
void RooLinTransBinning::binNumbers(double const * x, int * bins, std::size_t n, int coef) const
{
  // We are not allowed to modify the input array, so we can't apply the
  // transformation in-place and then call _input->binNumbers() without
  // allocating additional memory. That's why we fall back to binNumber() for
  // now. The RooLinTransBinning is only ever used in the RooLinearVar, so if
  // this ever becomes a bottleneck this could be optimized.
  for(std::size_t i = 0; i < n; ++i) {
    bins[i] += coef * _input->binNumber(invTrans(x[i]));
  }
}