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#ifndef HistogramGenerator_H
#define HistogramGenerator_H
#include "FastSimulation/Utilities/interface/BaseNumericalRandomGenerator.h"
#include "TH1.h"
/** Numerical Random Generator for Gamma distribution.
* Copy of LandauFluctuations
*/
class RandomEngine;
class TAxis;
class HistogramGenerator : public BaseNumericalRandomGenerator {
public:
/// Constructor : initialization of the Random Generator
HistogramGenerator(TH1* histo)
: BaseNumericalRandomGenerator(histo->GetXaxis()->GetXmin(), histo->GetXaxis()->GetXmax(), 100000, 3),
myHisto(histo),
theXaxis(histo->GetXaxis()),
nbins(histo->GetXaxis()->GetNbins()) {
// std::cout << "Old xmin/xmax = " << xmin << " " << xmax << std::endl;
// Drop lowest and highest empty bins
double du = (xmax - xmin) / (float)nbins;
// Restrict xmin to meaningful values
while (function(xmin) <= 0.)
xmin += du;
// Restrict xmax to meaningful values
while (function(xmax) <= 0.)
xmax -= du;
if (xmin != histo->GetXaxis()->GetXmin())
xmin -= du;
if (xmax != histo->GetXaxis()->GetXmax())
xmax += du;
// std::cout << "New xmin/xmax = " << xmin << " " << xmax << std::endl;
// std::cout <<" Init " << std::endl;
initialize();
}
/// Default destructor
~HistogramGenerator() override {}
/// The probability density function implementation
double function(double x) override { return ersatzt(x); }
private:
/// Pointer to the histogram
TH1* myHisto;
/// the axis
TAxis* theXaxis;
/// n bins
int nbins;
/// Gamma Function
double ersatzt(double x);
};
#endif
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