```/*****************************************************************************
* Project: RooFit                                                           *
* Package: RooFitModels                                                     *
* @(#)root/roofit:\$Id: RooGaussian.cxx 20878 2007-11-19 11:22:17Z rdm \$
* 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          *
*                                                                           *
* Redistribution and use in source and binary forms,                        *
* with or without modification, are permitted according to the terms        *
*****************************************************************************/

// -- CLASS DESCRIPTION [PDF] --
// Gaussian PDF...

#include "RooFit.h"

#include "Riostream.h"
#include "Riostream.h"
#include <math.h>

#include "RooGaussian.h"
#include "RooAbsReal.h"
#include "RooRealVar.h"
#include "RooRandom.h"
#include "RooMath.h"

ClassImp(RooGaussian)

RooGaussian::RooGaussian(const char *name, const char *title,
RooAbsReal& _x, RooAbsReal& _mean,
RooAbsReal& _sigma) :
RooAbsPdf(name,title),
x("x","Observable",this,_x),
mean("mean","Mean",this,_mean),
sigma("sigma","Width",this,_sigma)
{
}

RooGaussian::RooGaussian(const RooGaussian& other, const char* name) :
RooAbsPdf(other,name), x("x",this,other.x), mean("mean",this,other.mean),
sigma("sigma",this,other.sigma)
{
}

Double_t RooGaussian::evaluate() const
{
Double_t arg= x - mean;
return exp(-0.5*arg*arg/(sigma*sigma)) ;
}

Int_t RooGaussian::getAnalyticalIntegral(RooArgSet& allVars, RooArgSet& analVars, const char* /*rangeName*/) const
{
if (matchArgs(allVars,analVars,x)) return 1 ;
return 0 ;
}

Double_t RooGaussian::analyticalIntegral(Int_t code, const char* rangeName) const
{
assert(code==1) ;

static const Double_t root2 = sqrt(2.) ;
static const Double_t rootPiBy2 = sqrt(atan2(0.0,-1.0)/2.0);

Double_t xscale = root2*sigma;
return rootPiBy2*sigma*(RooMath::erf((x.max(rangeName)-mean)/xscale)-RooMath::erf((x.min(rangeName)-mean)/xscale));
}

Int_t RooGaussian::getGenerator(const RooArgSet& directVars, RooArgSet &generateVars, Bool_t /*staticInitOK*/) const
{
if (matchArgs(directVars,generateVars,x)) return 1 ;
return 0 ;
}

void RooGaussian::generateEvent(Int_t code)
{
assert(code==1) ;
Double_t xgen ;
while(1) {
xgen = RooRandom::randomGenerator()->Gaus(mean,sigma);
if (xgen<x.max() && xgen>x.min()) {
x = xgen ;
break;
}
}
return;
}

```

Last update: Thu Jan 17 08:44:50 2008

This page has been automatically generated. If you have any comments or suggestions about the page layout send a mail to ROOT support, or contact the developers with any questions or problems regarding ROOT.