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Diffstat (limited to 'libm/float/rgammaf.c')
-rw-r--r-- | libm/float/rgammaf.c | 130 |
1 files changed, 0 insertions, 130 deletions
diff --git a/libm/float/rgammaf.c b/libm/float/rgammaf.c deleted file mode 100644 index 5afa25e91..000000000 --- a/libm/float/rgammaf.c +++ /dev/null @@ -1,130 +0,0 @@ -/* rgammaf.c - * - * Reciprocal gamma function - * - * - * - * SYNOPSIS: - * - * float x, y, rgammaf(); - * - * y = rgammaf( x ); - * - * - * - * DESCRIPTION: - * - * Returns one divided by the gamma function of the argument. - * - * The function is approximated by a Chebyshev expansion in - * the interval [0,1]. Range reduction is by recurrence - * for arguments between -34.034 and +34.84425627277176174. - * 1/MAXNUMF is returned for positive arguments outside this - * range. - * - * The reciprocal gamma function has no singularities, - * but overflow and underflow may occur for large arguments. - * These conditions return either MAXNUMF or 1/MAXNUMF with - * appropriate sign. - * - * ACCURACY: - * - * Relative error: - * arithmetic domain # trials peak rms - * IEEE -34,+34 100000 8.9e-7 1.1e-7 - */ - -/* -Cephes Math Library Release 2.2: June, 1992 -Copyright 1985, 1987, 1992 by Stephen L. Moshier -Direct inquiries to 30 Frost Street, Cambridge, MA 02140 -*/ - -#include <math.h> - -/* Chebyshev coefficients for reciprocal gamma function - * in interval 0 to 1. Function is 1/(x gamma(x)) - 1 - */ - -static float R[] = { - 1.08965386454418662084E-9, --3.33964630686836942556E-8, - 2.68975996440595483619E-7, - 2.96001177518801696639E-6, --8.04814124978471142852E-5, - 4.16609138709688864714E-4, - 5.06579864028608725080E-3, --6.41925436109158228810E-2, --4.98558728684003594785E-3, - 1.27546015610523951063E-1 -}; - - -static char name[] = "rgammaf"; - -extern float PIF, MAXLOGF, MAXNUMF; - - - -float chbevlf(float, float *, int); -float expf(float), logf(float), sinf(float), lgamf(float); - -float rgammaf(float xx) -{ -float x, w, y, z; -int sign; - -x = xx; -if( x > 34.84425627277176174) - { - mtherr( name, UNDERFLOW ); - return(1.0/MAXNUMF); - } -if( x < -34.034 ) - { - w = -x; - z = sinf( PIF*w ); - if( z == 0.0 ) - return(0.0); - if( z < 0.0 ) - { - sign = 1; - z = -z; - } - else - sign = -1; - - y = logf( w * z / PIF ) + lgamf(w); - if( y < -MAXLOGF ) - { - mtherr( name, UNDERFLOW ); - return( sign * 1.0 / MAXNUMF ); - } - if( y > MAXLOGF ) - { - mtherr( name, OVERFLOW ); - return( sign * MAXNUMF ); - } - return( sign * expf(y)); - } -z = 1.0; -w = x; - -while( w > 1.0 ) /* Downward recurrence */ - { - w -= 1.0; - z *= w; - } -while( w < 0.0 ) /* Upward recurrence */ - { - z /= w; - w += 1.0; - } -if( w == 0.0 ) /* Nonpositive integer */ - return(0.0); -if( w == 1.0 ) /* Other integer */ - return( 1.0/z ); - -y = w * ( 1.0 + chbevlf( 4.0*w-2.0, R, 10 ) ) / z; -return(y); -} |