G4ChebyshevApproximation Class Reference

#include <G4ChebyshevApproximation.hh>


Public Member Functions

 G4ChebyshevApproximation (function pFunction, G4int n, G4double a, G4double b)
 G4ChebyshevApproximation (function pFunction, G4int n, G4int m, G4double a, G4double b)
 G4ChebyshevApproximation (function pFunction, G4double a, G4double b, G4int n)
 ~G4ChebyshevApproximation ()
G4double GetChebyshevCof (G4int number) const
G4double ChebyshevEvaluation (G4double x) const
void DerivativeChebyshevCof (G4double derCof[]) const
void IntegralChebyshevCof (G4double integralCof[]) const

Detailed Description

Definition at line 128 of file G4ChebyshevApproximation.hh.

Constructor & Destructor Documentation

G4ChebyshevApproximation::G4ChebyshevApproximation ( function  pFunction,
G4int  n,
G4double  a,
G4double  b 
)

Definition at line 39 of file G4ChebyshevApproximation.cc.

References G4INCL::Math::pi.

00043    : fFunction(pFunction), fNumber(n),
00044      fChebyshevCof(new G4double[fNumber]),
00045      fMean(0.5*(b+a)), fDiff(0.5*(b-a))
00046 {
00047    G4int i=0, j=0 ;
00048    G4double  rootSum=0.0, cofj=0.0 ;
00049    G4double* tempFunction = new G4double[fNumber] ;
00050    G4double weight = 2.0/fNumber ;
00051    G4double cof = 0.5*weight*pi ;    // pi/n
00052    
00053    for (i=0;i<fNumber;i++)
00054    {
00055       rootSum = std::cos(cof*(i+0.5)) ;
00056       tempFunction[i]= fFunction(rootSum*fDiff+fMean) ;
00057    }
00058    for (j=0;j<fNumber;j++) 
00059    {
00060       cofj = cof*j ;
00061       rootSum = 0.0 ;
00062       
00063       for (i=0;i<fNumber;i++)
00064       {
00065          rootSum += tempFunction[i]*std::cos(cofj*(i+0.5)) ;
00066       }
00067       fChebyshevCof[j] = weight*rootSum ;
00068    }
00069    delete[] tempFunction ;
00070 }

G4ChebyshevApproximation::G4ChebyshevApproximation ( function  pFunction,
G4int  n,
G4int  m,
G4double  a,
G4double  b 
)

Definition at line 80 of file G4ChebyshevApproximation.cc.

References DerivativeChebyshevCof(), FatalException, G4Exception(), and G4INCL::Math::pi.

00083    : fFunction(pFunction), fNumber(nx),
00084      fChebyshevCof(new G4double[fNumber]),
00085      fMean(0.5*(b+a)), fDiff(0.5*(b-a))
00086 {
00087    if(nx <= mx)
00088    {
00089       G4Exception("G4ChebyshevApproximation::G4ChebyshevApproximation()",
00090                   "InvalidCall", FatalException, "Invalid arguments !") ;
00091    }
00092    G4int i=0, j=0 ;
00093    G4double  rootSum = 0.0, cofj=0.0;   
00094    G4double* tempFunction = new G4double[fNumber] ;
00095    G4double weight = 2.0/fNumber ;
00096    G4double cof = 0.5*weight*pi ;    // pi/nx
00097    
00098    for (i=0;i<fNumber;i++)
00099    {
00100       rootSum = std::cos(cof*(i+0.5)) ;
00101       tempFunction[i] = fFunction(rootSum*fDiff+fMean) ;
00102    }
00103    for (j=0;j<fNumber;j++) 
00104    {
00105       cofj = cof*j ;
00106       rootSum = 0.0 ;
00107       
00108       for (i=0;i<fNumber;i++)
00109       {
00110          rootSum += tempFunction[i]*std::cos(cofj*(i+0.5)) ;
00111       }
00112       fChebyshevCof[j] = weight*rootSum ; // corresponds to pFunction
00113    }
00114    // Chebyshev coefficients for (mx)-derivative of pFunction
00115    
00116    for(i=1;i<=mx;i++)
00117    {
00118       DerivativeChebyshevCof(tempFunction) ;
00119       fNumber-- ;
00120       for(j=0;j<fNumber;j++)
00121       {
00122         fChebyshevCof[j] = tempFunction[j] ; // corresponds to (i)-derivative
00123       }
00124    }
00125    delete[] tempFunction ;   // delete of dynamically allocated tempFunction
00126 }

G4ChebyshevApproximation::G4ChebyshevApproximation ( function  pFunction,
G4double  a,
G4double  b,
G4int  n 
)

Definition at line 133 of file G4ChebyshevApproximation.cc.

References IntegralChebyshevCof(), and G4INCL::Math::pi.

00137    : fFunction(pFunction), fNumber(n),
00138      fChebyshevCof(new G4double[fNumber]),
00139      fMean(0.5*(b+a)), fDiff(0.5*(b-a))
00140 {
00141    G4int i=0, j=0;
00142    G4double  rootSum=0.0, cofj=0.0;
00143    G4double* tempFunction = new G4double[fNumber] ;
00144    G4double weight = 2.0/fNumber;
00145    G4double cof = 0.5*weight*pi ;    // pi/n
00146    
00147    for (i=0;i<fNumber;i++)
00148    {
00149       rootSum = std::cos(cof*(i+0.5)) ;
00150       tempFunction[i]= fFunction(rootSum*fDiff+fMean) ;
00151    }
00152    for (j=0;j<fNumber;j++) 
00153    {
00154       cofj = cof*j ;
00155       rootSum = 0.0 ;
00156       
00157       for (i=0;i<fNumber;i++)
00158       {
00159          rootSum += tempFunction[i]*std::cos(cofj*(i+0.5)) ;
00160       }
00161       fChebyshevCof[j] = weight*rootSum ; // corresponds to pFunction
00162    }
00163    // Chebyshev coefficients for integral of pFunction
00164    
00165    IntegralChebyshevCof(tempFunction) ;
00166    for(j=0;j<fNumber;j++)
00167    {
00168       fChebyshevCof[j] = tempFunction[j] ; // corresponds to integral
00169    }
00170    delete[] tempFunction ;   // delete of dynamically allocated tempFunction
00171 }

G4ChebyshevApproximation::~G4ChebyshevApproximation (  ) 

Definition at line 179 of file G4ChebyshevApproximation.cc.

00180 {
00181    delete[] fChebyshevCof ;
00182 }

Member Function Documentation

G4double G4ChebyshevApproximation::ChebyshevEvaluation ( G4double  x  )  const

Definition at line 207 of file G4ChebyshevApproximation.cc.

References FatalException, and G4Exception().

00208 {
00209    G4double evaluate = 0.0, evaluate2 = 0.0, temp = 0.0,
00210             xReduced = 0.0, xReduced2 = 0.0 ;
00211 
00212    if ((x-fMean+fDiff)*(x-fMean-fDiff) > 0.0) 
00213    {
00214       G4Exception("G4ChebyshevApproximation::ChebyshevEvaluation()",
00215                   "InvalidCall", FatalException, "Invalid argument !") ;
00216    }
00217    xReduced = (x-fMean)/fDiff ;
00218    xReduced2 = 2.0*xReduced ;
00219    for (G4int i=fNumber-1;i>=1;i--) 
00220    {
00221      temp = evaluate ;
00222      evaluate  = xReduced2*evaluate - evaluate2 + fChebyshevCof[i] ;
00223      evaluate2 = temp ;
00224    }
00225    return xReduced*evaluate - evaluate2 + 0.5*fChebyshevCof[0] ;
00226 }

void G4ChebyshevApproximation::DerivativeChebyshevCof ( G4double  derCof[]  )  const

Definition at line 234 of file G4ChebyshevApproximation.cc.

Referenced by G4ChebyshevApproximation().

00235 {
00236    G4double cof = 1.0/fDiff ;
00237    derCof[fNumber-1] = 0.0 ;
00238    derCof[fNumber-2] = 2*(fNumber-1)*fChebyshevCof[fNumber-1] ;
00239    for(G4int i=fNumber-3;i>=0;i--)
00240    {
00241       derCof[i] = derCof[i+2] + 2*(i+1)*fChebyshevCof[i+1] ;  
00242    }
00243    for(G4int j=0;j<fNumber;j++)
00244    {
00245       derCof[j] *= cof ;
00246    }
00247 }

G4double G4ChebyshevApproximation::GetChebyshevCof ( G4int  number  )  const

Definition at line 191 of file G4ChebyshevApproximation.cc.

References FatalException, and G4Exception().

00192 {
00193    if(number < 0 && number >= fNumber)
00194    {
00195       G4Exception("G4ChebyshevApproximation::GetChebyshevCof()",
00196                   "InvalidCall", FatalException, "Argument out of range !") ;
00197    }
00198    return fChebyshevCof[number] ;
00199 }

void G4ChebyshevApproximation::IntegralChebyshevCof ( G4double  integralCof[]  )  const

Definition at line 259 of file G4ChebyshevApproximation.cc.

Referenced by G4ChebyshevApproximation().

00260 {
00261    G4double cof = 0.5*fDiff, sum = 0.0, factor = 1.0 ;
00262    for(G4int i=1;i<fNumber-1;i++)
00263    {
00264       integralCof[i] = cof*(fChebyshevCof[i-1] - fChebyshevCof[i+1])/i ;
00265       sum += factor*integralCof[i] ;
00266       factor = -factor ;
00267    }
00268    integralCof[fNumber-1] = cof*fChebyshevCof[fNumber-2]/(fNumber-1) ;
00269    sum += factor*integralCof[fNumber-1] ;
00270    integralCof[0] = 2.0*sum ;                // set the constant of integration
00271 }

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