#include <RandArrayFunction.h>

Public Member Functions
double	Fire () const

void	FireArray (int size, double *array) const

double	operator() () const

void	PrepareTable (const double *aProbFunc)

	RandArrayFunction (const double *aProbFunc, int theProbSize, int interpolationType=0)

	RandArrayFunction (int probSize, int interpolationType=0)

double	Shoot () const

void	ShootArray (int size, double *array) const

Private Member Functions
double	MapRandom (double rand) const

double	StandardRand () const

void	UseFlatDistribution ()

Private Attributes
std::vector< double >	fIntegralPdf

int	fInterpolationType

int	fNBins

double	fOneOverNbins

Detailed Description

Definition at line 73 of file RandArrayFunction.h.

Constructor & Destructor Documentation

RandArrayFunction::RandArrayFunction	(	const double *	aProbFunc,
		int	theProbSize,
		int	interpolationType = `0`
	)

Definition at line 12 of file RandArrayFunction.cc.

References PrepareTable().

   : fNBins(theProbSize), 
     fInterpolationType(intType)
 {
   PrepareTable(aProbFunc);
 }

RandArrayFunction::RandArrayFunction	(	int	probSize,
		int	interpolationType = `0`
	)

Definition at line 19 of file RandArrayFunction.cc.

   : fNBins(theProbSize), 
     fInterpolationType(intType)
 {}

Member Function Documentation

double RandArrayFunction::Fire ( ) const

inline

Definition at line 102 of file RandArrayFunction.h.

References MapRandom(), and StandardRand().

Referenced by FireArray(), operator()(), and Shoot().

                                             {
   return MapRandom(StandardRand());
 }

void RandArrayFunction::FireArray	(	int	size,
		double *	array
	)		const

Definition at line 113 of file RandArrayFunction.cc.

References Fire(), mps_fire::i, and findQualityFiles::size.

Referenced by ShootArray().

                                                               {
   for (int i = 0; i < size; ++i)
     vect[i] = Fire();
 }

double RandArrayFunction::MapRandom ( double rand ) const

private

Definition at line 73 of file RandArrayFunction.cc.

References fIntegralPdf, fInterpolationType, fNBins, and fOneOverNbins.

Referenced by Fire().

                                                      {
   // Private method to take the random (however it is created) and map it
   // according to the distribution.
 
   int nBelow = 0;     // largest k such that I[k] is known to be <= rand
   int nAbove = fNBins;  // largest k such that I[k] is known to be >  rand
   int middle;
      
   while (nAbove > nBelow+1) {
     middle = (nAbove + nBelow+1)>>1;
     rand >= fIntegralPdf[middle] ? nBelow = middle : nAbove = middle;
   }// after this loop, nAbove is always nBelow+1 and they straddle rad:
        
   /*assert ( nAbove = nBelow+1 );
     assert ( fIntegralPdf[nBelow] <= rand );
     assert ( fIntegralPdf[nAbove] >= rand );*/  
   // If a defective engine produces rand=1, that will 
   // still give sensible results so we relax the > rand assertion
 
   if (fInterpolationType == 1) {
     return nBelow * fOneOverNbins;
   } 
   else {
     double binMeasure = fIntegralPdf[nAbove] - fIntegralPdf[nBelow];
     // binMeasure is always aProbFunc[nBelow], 
     // but we don't have aProbFunc any more so we subtract.
     
     if (!binMeasure) { 
       // rand lies right in a bin of measure 0.  Simply return the center
       // of the range of that bin.  (Any value between k/N and (k+1)/N is 
       // equally good, in this rare case.)
       return (nBelow + .5) * fOneOverNbins;
     }
 
     double binFraction = (rand - fIntegralPdf[nBelow]) / binMeasure;
     
     return (nBelow + binFraction) * fOneOverNbins;
   }
 } 

double RandArrayFunction::operator() ( ) const

inline

Definition at line 110 of file RandArrayFunction.h.

References Fire().

                                                   {
   return Fire();
 }

void RandArrayFunction::PrepareTable ( const double * aProbFunc )

Definition at line 24 of file RandArrayFunction.cc.

References fIntegralPdf, fInterpolationType, fNBins, fOneOverNbins, UseFlatDistribution(), and mps_merge::weight.

Referenced by gen::Hydjet2Hadronizer::generatePartonsAndHadronize(), and RandArrayFunction().

                                                             {
   //Prepares fIntegralPdf.
   if(fNBins < 1) {
     edm::LogError("RandArrayFunction") << "RandArrayFunction constructed with no bins - will use flat distribution";
     UseFlatDistribution();
     return;
   }
 
   fIntegralPdf.resize(fNBins + 1);
   fIntegralPdf[0] = 0;
   int ptn;
   for (ptn = 0; ptn < fNBins; ++ptn ) {
     double weight = aProbFunc[ptn];
     if (weight < 0.) {
       // We can't stomach negative bin contents, they invalidate the 
       // search algorithm when the distribution is fired.
       edm::LogWarning("RandArrayFunction") << "RandArrayFunction constructed with negative-weight bin "<< ptn << " == " << weight << " -- will substitute 0 weight";
       weight = 0.;
     }
     fIntegralPdf[ptn + 1] = fIntegralPdf[ptn] + weight;
   }
 
   if (fIntegralPdf[fNBins] <= 0.) {
     edm::LogWarning("RandArrayFunction") << "RandArrayFunction constructed with nothing in bins - will use flat distribution";
     UseFlatDistribution();
     return;
   }
 
   for (ptn = 0; ptn < fNBins + 1; ++ptn)
     fIntegralPdf[ptn] /= fIntegralPdf[fNBins];
   
   // And another useful variable is ...
   fOneOverNbins = 1.0 / fNBins;
   // One last chore:
   if (fInterpolationType && fInterpolationType != 1) {
     edm::LogInfo("RandArrayFunction") << "RandArrayFunction does not recognize fInterpolationType "<< fInterpolationType << " Will use type 0 (continuous linear interpolation)";
     fInterpolationType = 0;
   }
 } 

double RandArrayFunction::Shoot ( ) const

inline

Definition at line 106 of file RandArrayFunction.h.

References Fire().

                                              {
   return Fire();
 }

void RandArrayFunction::ShootArray	(	int	size,
		double *	array
	)		const

inline

Definition at line 114 of file RandArrayFunction.h.

References FireArray().

                                                                        {
   FireArray(size, array);
 }

double RandArrayFunction::StandardRand ( ) const

inlineprivate

Definition at line 98 of file RandArrayFunction.h.

References hjRandomEngine.

Referenced by Fire().

                                                     {
   return CLHEP::RandFlat::shoot(hjRandomEngine);
 }

void RandArrayFunction::UseFlatDistribution ( )

private

Definition at line 64 of file RandArrayFunction.cc.

References fIntegralPdf, fNBins, and fOneOverNbins.

Referenced by PrepareTable().

                                             {
   //Called only by PrepareTable in case of user error. 
   fNBins = 1;
   fIntegralPdf.resize(2);
   fIntegralPdf[0] = 0;
   fIntegralPdf[1] = 1;
   fOneOverNbins = 1.0;
 } 