Gabriele Cosmo
240 lines
6.1 KiB
C++
240 lines
6.1 KiB
C++
//
|
|
// ********************************************************************
|
|
// * License and Disclaimer *
|
|
// * *
|
|
// * The Geant4 software is copyright of the Copyright Holders of *
|
|
// * the Geant4 Collaboration. It is provided under the terms and *
|
|
// * conditions of the Geant4 Software License, included in the file *
|
|
// * LICENSE and available at http://cern.ch/geant4/license . These *
|
|
// * include a list of copyright holders. *
|
|
// * *
|
|
// * Neither the authors of this software system, nor their employing *
|
|
// * institutes,nor the agencies providing financial support for this *
|
|
// * work make any representation or warranty, express or implied, *
|
|
// * regarding this software system or assume any liability for its *
|
|
// * use. Please see the license in the file LICENSE and URL above *
|
|
// * for the full disclaimer and the limitation of liability. *
|
|
// * *
|
|
// * This code implementation is the result of the scientific and *
|
|
// * technical work of the GEANT4 collaboration. *
|
|
// * By using, copying, modifying or distributing the software (or *
|
|
// * any work based on the software) you agree to acknowledge its *
|
|
// * use in resulting scientific publications, and indicate your *
|
|
// * acceptance of all terms of the Geant4 Software license. *
|
|
// ********************************************************************
|
|
//
|
|
// G4Pow
|
|
//
|
|
// Class description:
|
|
//
|
|
// Utility singleton class for the fast computation of log and pow
|
|
// functions. Integer argument should be in the interval 0-512, no
|
|
// check is performed inside these methods for performance reasons.
|
|
// For factorial integer argument should be in the interval 0-170
|
|
// Computations with double arguments are fast for the interval
|
|
// 0.002-511.5 for all functions except exponent, which is computed
|
|
// for the interval 0-84.4, standard library is used in the opposite case
|
|
|
|
// Author: Vladimir Ivanchenko, 23.05.2009
|
|
// --------------------------------------------------------------------
|
|
#ifndef G4Pow_hh
|
|
#define G4Pow_hh 1
|
|
|
|
#include "G4DataVector.hh"
|
|
#include "G4Exp.hh"
|
|
#include "G4Log.hh"
|
|
#include "globals.hh"
|
|
|
|
class G4Pow
|
|
{
|
|
public:
|
|
static G4Pow* GetInstance();
|
|
~G4Pow() = default;
|
|
|
|
// Fast computation of Z^1/3
|
|
//
|
|
inline G4double Z13(G4int Z) const;
|
|
G4double A13(G4double A) const;
|
|
|
|
// Fast computation of Z^2/3
|
|
//
|
|
inline G4double Z23(G4int Z) const;
|
|
inline G4double A23(G4double A) const;
|
|
|
|
// Fast computation of log(Z)
|
|
//
|
|
inline G4double logZ(G4int Z) const;
|
|
inline G4double logA(G4double A) const;
|
|
inline G4double logX(G4double x) const;
|
|
|
|
// Fast computation of log10(Z)
|
|
//
|
|
inline G4double log10Z(G4int Z) const;
|
|
inline G4double log10A(G4double A) const;
|
|
|
|
// Fast computation of exp(X)
|
|
//
|
|
inline G4double expA(G4double A) const;
|
|
|
|
// Fast computation of pow(Z,X)
|
|
//
|
|
inline G4double powZ(G4int Z, G4double y) const;
|
|
inline G4double powA(G4double A, G4double y) const;
|
|
G4double powN(G4double x, G4int n) const;
|
|
|
|
// Fast factorial
|
|
//
|
|
inline G4double factorial(G4int Z) const;
|
|
inline G4double logfactorial(G4int Z) const;
|
|
|
|
private:
|
|
G4Pow();
|
|
|
|
G4double A13Low(const G4double, const G4bool) const;
|
|
G4double A13High(const G4double, const G4bool) const;
|
|
|
|
inline G4double logBase(G4double x) const;
|
|
|
|
static G4Pow* fpInstance;
|
|
|
|
const G4double onethird = 1.0 / 3.0;
|
|
const G4int max2 = 5;
|
|
|
|
G4double maxA;
|
|
G4double maxLowA;
|
|
G4double maxA2;
|
|
G4double maxAexp;
|
|
|
|
G4DataVector ener;
|
|
G4DataVector logen;
|
|
G4DataVector pz13;
|
|
G4DataVector lowa13;
|
|
G4DataVector lz;
|
|
G4DataVector lz2;
|
|
G4DataVector fexp;
|
|
G4DataVector fact;
|
|
G4DataVector logfact;
|
|
};
|
|
|
|
// -----------------------------
|
|
// Inline methods implementation
|
|
// -----------------------------
|
|
|
|
inline G4double G4Pow::Z13(G4int Z) const { return pz13[Z]; }
|
|
|
|
inline G4double G4Pow::Z23(G4int Z) const
|
|
{
|
|
G4double x = Z13(Z);
|
|
return x * x;
|
|
}
|
|
|
|
inline G4double G4Pow::A23(G4double A) const
|
|
{
|
|
G4double x = A13(A);
|
|
return x * x;
|
|
}
|
|
|
|
inline G4double G4Pow::logZ(G4int Z) const { return lz[Z]; }
|
|
|
|
inline G4double G4Pow::logBase(G4double a) const
|
|
{
|
|
G4double res;
|
|
if(a <= maxA2)
|
|
{
|
|
G4int i = G4int(max2 * (a - 1) + 0.5);
|
|
if(i > max2)
|
|
{
|
|
i = max2;
|
|
}
|
|
G4double x = a / (G4double(i) / max2 + 1) - 1;
|
|
res = lz2[i] + x * (1.0 - (0.5 - onethird * x) * x);
|
|
}
|
|
else if(a <= maxA)
|
|
{
|
|
G4int i = G4int(a + 0.5);
|
|
G4double x = a / G4double(i) - 1;
|
|
res = lz[i] + x * (1.0 - (0.5 - onethird * x) * x);
|
|
}
|
|
else
|
|
{
|
|
res = G4Log(a);
|
|
}
|
|
return res;
|
|
}
|
|
|
|
inline G4double G4Pow::logA(G4double A) const
|
|
{
|
|
return (1.0 <= A ? logBase(A) : -logBase(1. / A));
|
|
}
|
|
|
|
inline G4double G4Pow::logX(G4double x) const
|
|
{
|
|
G4double res = 0.0;
|
|
G4double a = (1.0 <= x) ? x : 1.0 / x;
|
|
|
|
if(a <= maxA)
|
|
{
|
|
res = logBase(a);
|
|
}
|
|
else if(a <= ener[2])
|
|
{
|
|
res = logen[1] + logBase(a / ener[1]);
|
|
}
|
|
else if(a <= ener[3])
|
|
{
|
|
res = logen[2] + logBase(a / ener[2]);
|
|
}
|
|
else
|
|
{
|
|
res = G4Log(a);
|
|
}
|
|
|
|
if(1.0 > x)
|
|
{
|
|
res = -res;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
inline G4double G4Pow::log10Z(G4int Z) const { return lz[Z] / lz[10]; }
|
|
|
|
inline G4double G4Pow::log10A(G4double A) const { return logX(A) / lz[10]; }
|
|
|
|
inline G4double G4Pow::expA(G4double A) const
|
|
{
|
|
G4double res;
|
|
G4double a = (0.0 <= A) ? A : -A;
|
|
|
|
if(a <= maxAexp)
|
|
{
|
|
G4int i = G4int(2 * a + 0.5);
|
|
G4double x = a - i * 0.5;
|
|
res = fexp[i] * (1.0 + x * (1.0 + 0.5 * (1.0 + onethird * x) * x));
|
|
}
|
|
else
|
|
{
|
|
res = G4Exp(a);
|
|
}
|
|
if(0.0 > A)
|
|
{
|
|
res = 1.0 / res;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
inline G4double G4Pow::powZ(G4int Z, G4double y) const
|
|
{
|
|
return expA(y * lz[Z]);
|
|
}
|
|
|
|
inline G4double G4Pow::powA(G4double A, G4double y) const
|
|
{
|
|
return (0.0 == A ? 0.0 : expA(y * logX(A)));
|
|
}
|
|
|
|
inline G4double G4Pow::factorial(G4int Z) const { return fact[Z]; }
|
|
|
|
inline G4double G4Pow::logfactorial(G4int Z) const { return logfact[Z]; }
|
|
|
|
#endif
|