G4Exp.hh File Reference

#include <limits>
#include <stdint.h>
#include "G4Types.hh"

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Classes
union	G4ExpConsts::ieee754

Namespaces
	G4ExpConsts

Functions
G4double	G4ExpConsts::uint642dp (uint64_t ll)
G4float	G4ExpConsts::uint322sp (G4int x)
uint32_t	G4ExpConsts::sp2uint32 (G4float x)
G4double	G4ExpConsts::fpfloor (const G4double x)
G4float	G4ExpConsts::fpfloor (const G4float x)
G4double	G4Exp (G4double initial_x)
	Exponential Function double precision. More...
G4float	G4Expf (G4float initial_x)
	Exponential Function single precision. More...
void	expv (const uint32_t size, G4double const *__restrict__ iarray, G4double *__restrict__ oarray)
void	G4Expv (const uint32_t size, G4double const *__restrict__ iarray, G4double *__restrict__ oarray)
void	expfv (const uint32_t size, G4float const *__restrict__ iarray, G4float *__restrict__ oarray)
void	G4Expfv (const uint32_t size, G4float const *__restrict__ iarray, G4float *__restrict__ oarray)

Variables
const G4double	G4ExpConsts::EXP_LIMIT = 708
const G4double	G4ExpConsts::PX1exp = 1.26177193074810590878E-4
const G4double	G4ExpConsts::PX2exp = 3.02994407707441961300E-2
const G4double	G4ExpConsts::PX3exp = 9.99999999999999999910E-1
const G4double	G4ExpConsts::QX1exp = 3.00198505138664455042E-6
const G4double	G4ExpConsts::QX2exp = 2.52448340349684104192E-3
const G4double	G4ExpConsts::QX3exp = 2.27265548208155028766E-1
const G4double	G4ExpConsts::QX4exp = 2.00000000000000000009E0
const G4double	G4ExpConsts::LOG2E = 1.4426950408889634073599
const G4float	G4ExpConsts::MAXLOGF = 88.72283905206835f
const G4float	G4ExpConsts::MINLOGF = -88.f
const G4float	G4ExpConsts::C1F = 0.693359375f
const G4float	G4ExpConsts::C2F = -2.12194440e-4f
const G4float	G4ExpConsts::PX1expf = 1.9875691500E-4f
const G4float	G4ExpConsts::PX2expf =1.3981999507E-3f
const G4float	G4ExpConsts::PX3expf =8.3334519073E-3f
const G4float	G4ExpConsts::PX4expf =4.1665795894E-2f
const G4float	G4ExpConsts::PX5expf =1.6666665459E-1f
const G4float	G4ExpConsts::PX6expf =5.0000001201E-1f
const G4float	G4ExpConsts::LOG2EF = 1.44269504088896341f

Function Documentation

void expfv	(	const uint32_t	size,
		G4float const *__restrict__	iarray,
		G4float *__restrict__	oarray
	)

void expv	(	const uint32_t	size,
		G4double const *__restrict__	iarray,
		G4double *__restrict__	oarray
	)

G4double G4Exp ( G4double  initial_x )

inline

Exponential Function double precision.

Definition at line 183 of file G4Exp.hh.

{
    G4double x = initial_x;
    G4double px=G4ExpConsts::fpfloor(G4ExpConsts::LOG2E * x +0.5);
 
    const int32_t n = int32_t(px);

    x -= px * 6.93145751953125E-1;
    x -= px * 1.42860682030941723212E-6;

    const G4double xx = x * x;

    // px = x * P(x**2).
    px = G4ExpConsts::PX1exp;
    px *= xx;
    px += G4ExpConsts::PX2exp;
    px *= xx;
    px += G4ExpConsts::PX3exp;
    px *= x;

    // Evaluate Q(x**2).
    G4double qx = G4ExpConsts::QX1exp;
    qx *= xx;
    qx += G4ExpConsts::QX2exp;
    qx *= xx;
    qx += G4ExpConsts::QX3exp;
    qx *= xx;
    qx += G4ExpConsts::QX4exp;

    // e**x = 1 + 2x P(x**2)/( Q(x**2) - P(x**2) )
    x = px / (qx - px);
    x = 1.0 + 2.0 * x;

    // Build 2^n in double.
    x *= G4ExpConsts::uint642dp(( ((uint64_t)n) +1023)<<52);

    if (initial_x > G4ExpConsts::EXP_LIMIT)
            x = std::numeric_limits<G4double>::infinity();
    if (initial_x < -G4ExpConsts::EXP_LIMIT)
            x = 0.;

    return x;
}

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G4float G4Expf ( G4float  initial_x )

inline

Exponential Function single precision.

Definition at line 230 of file G4Exp.hh.

{
    G4float x = initial_x;

    G4float z = G4ExpConsts::fpfloor( G4ExpConsts::LOG2EF * x +0.5f ); /* std::floor() truncates toward -infinity. */

    x -= z * G4ExpConsts::C1F;
    x -= z * G4ExpConsts::C2F;
    const int32_t n = int32_t ( z );

    const G4float x2 = x * x;

    z = x*G4ExpConsts::PX1expf;
    z += G4ExpConsts::PX2expf;
    z *= x;
    z += G4ExpConsts::PX3expf;
    z *= x;
    z += G4ExpConsts::PX4expf;
    z *= x;
    z += G4ExpConsts::PX5expf;
    z *= x;
    z += G4ExpConsts::PX6expf;
    z *= x2;
    z += x + 1.0f;

    /* multiply by power of 2 */
    z *=  G4ExpConsts::uint322sp((n+0x7f)<<23);

    if (initial_x > G4ExpConsts::MAXLOGF) z=std::numeric_limits<G4float>::infinity();
    if (initial_x < G4ExpConsts::MINLOGF) z=0.f;

    return z;
}

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void G4Expfv	(	const uint32_t	size,
		G4float const *__restrict__	iarray,
		G4float *__restrict__	oarray
	)

void G4Expv	(	const uint32_t	size,
		G4double const *__restrict__	iarray,
		G4double *__restrict__	oarray
	)