G4SimpleIntegration Class Reference

#include <G4SimpleIntegration.hh>

Public Member Functions
	G4SimpleIntegration (function pFunction)
	G4SimpleIntegration (function pFunction, G4double pTolerance)
	~G4SimpleIntegration ()
G4double	Trapezoidal (G4double xInitial, G4double xFinal, G4int iterationNumber)
G4double	MidPoint (G4double xInitial, G4double xFinal, G4int iterationNumber)
G4double	Gauss (G4double xInitial, G4double xFinal, G4int iterationNumber)
G4double	Simpson (G4double xInitial, G4double xFinal, G4int iterationNumber)
G4double	AdaptGaussIntegration (G4double xInitial, G4double xFinal)

Protected Member Functions
G4double	Gauss (G4double xInitial, G4double xFinal)
void	AdaptGauss (G4double xInitial, G4double xFinal, G4double &sum, G4int &depth)

Detailed Description

Definition at line 64 of file G4SimpleIntegration.hh.

Constructor & Destructor Documentation

G4SimpleIntegration::G4SimpleIntegration ( function  pFunction )

explicit

Definition at line 36 of file G4SimpleIntegration.cc.

   : fFunction(pFunction),
     fTolerance(.0001),
     fMaxDepth(100)
{
}

G4SimpleIntegration::G4SimpleIntegration	(	function	pFunction,
		G4double	pTolerance
	)

Definition at line 43 of file G4SimpleIntegration.cc.

   : fFunction(pFunction),
     fTolerance(pTolerance),
     fMaxDepth(100)
{
}

G4SimpleIntegration::~G4SimpleIntegration

(

)

Definition at line 52 of file G4SimpleIntegration.cc.

{
}

Member Function Documentation

void G4SimpleIntegration::AdaptGauss ( G4double  xInitial, G4double  xFinal, G4double &  sum, G4int &  depth  )

protected

Definition at line 160 of file G4SimpleIntegration.cc.

{
   if(depth >fMaxDepth)
   {
      G4Exception("G4SimpleIntegration::AdaptGauss()", "Error",
                  FatalException, "Function varies too rapidly !") ;
   }
   G4double xMean = (xInitial + xFinal)/2.0 ;
   G4double leftHalf = Gauss(xInitial,xMean) ;
   G4double rightHalf = Gauss(xMean,xFinal) ;
   G4double full = Gauss(xInitial,xFinal) ;
   if(std::fabs(leftHalf+rightHalf-full) < fTolerance)
   {
      sum += full ;
   }
   else
   {
      depth++ ;
      AdaptGauss(xInitial,xMean,sum,depth) ;
      AdaptGauss(xMean,xFinal,sum,depth) ;
   }
}

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G4double G4SimpleIntegration::AdaptGaussIntegration	(	G4double	xInitial,
		G4double	xFinal
	)

Definition at line 134 of file G4SimpleIntegration.cc.

{
   G4int depth = 0 ;
   G4double sum = 0.0 ;
   AdaptGauss(xInitial,xFinal,sum,depth) ;
   return sum ;
}

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G4double G4SimpleIntegration::Gauss	(	G4double	xInitial,
		G4double	xFinal,
		G4int	iterationNumber
	)

Definition at line 91 of file G4SimpleIntegration.cc.

{
   G4double x=0.;
   static const G4double root = 1.0/std::sqrt(3.0) ;
   G4double Step = (xFinal - xInitial)/(2.0*iterationNumber) ;
   G4double delta = Step*root ;
   G4double mean = 0.0 ;
   for(G4int i=0;i<iterationNumber;i++)
   {
      x = (2*i + 1)*Step ;
      mean += (fFunction(x+delta) + fFunction(x-delta)) ;
   }
   return mean*Step ;   
}

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G4double G4SimpleIntegration::Gauss ( G4double  xInitial, G4double  xFinal  )

protected

Definition at line 145 of file G4SimpleIntegration.cc.

{
   static const G4double root = 1.0/std::sqrt(3.0) ;
   
   G4double xMean = (xInitial + xFinal)/2.0 ;
   G4double Step = (xFinal - xInitial)/2.0 ;
   G4double delta = Step*root ;
   G4double sum = (fFunction(xMean + delta) + fFunction(xMean - delta)) ;
   
   return sum*Step ;   
}

G4double G4SimpleIntegration::MidPoint	(	G4double	xInitial,
		G4double	xFinal,
		G4int	iterationNumber
	)

Definition at line 75 of file G4SimpleIntegration.cc.

{
   G4double Step = (xFinal - xInitial)/iterationNumber ;
   G4double x = xInitial + 0.5*Step;
   G4double mean = fFunction(x) ;
   for(G4int i=1;i<iterationNumber;i++)
   {
      x += Step ;
      mean += fFunction(x) ;
   }
   return mean*Step ;   
}

G4double G4SimpleIntegration::Simpson	(	G4double	xInitial,
		G4double	xFinal,
		G4int	iterationNumber
	)

Definition at line 109 of file G4SimpleIntegration.cc.

{
   G4double Step = (xFinal - xInitial)/iterationNumber ;
   G4double x = xInitial ;
   G4double xPlus = xInitial + 0.5*Step ;
   G4double mean = (fFunction(xInitial) + fFunction(xFinal))*0.5 ;
   G4double sum = fFunction(xPlus) ;
   for(G4int i=1;i<iterationNumber;i++)
   {
      x     += Step ;
      xPlus += Step ;
      mean  += fFunction(x) ;
      sum   += fFunction(xPlus) ;
   }
   mean += 2.0*sum ;
   return mean*Step/3.0 ;   
}

G4double G4SimpleIntegration::Trapezoidal	(	G4double	xInitial,
		G4double	xFinal,
		G4int	iterationNumber
	)

Definition at line 59 of file G4SimpleIntegration.cc.

{
   G4double Step = (xFinal - xInitial)/iterationNumber ;
   G4double mean = (fFunction(xInitial) + fFunction(xFinal))*0.5 ;
   G4double x = xInitial ;
   for(G4int i=1;i<iterationNumber;i++)
   {
      x += Step ;
      mean += fFunction(x) ;
   }
   return mean*Step ;
}

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The documentation for this class was generated from the following files:

• geant4.10.03.p01/source/global/HEPNumerics/include/G4SimpleIntegration.hh
• geant4.10.03.p01/source/global/HEPNumerics/src/G4SimpleIntegration.cc