wrf_gamma.c

来自「标准c库代码,可以应用于各个系统提供了大量的基本函数」· C语言 代码 · 共 54 行

/* wrf_gamma.c -- float version of wr_gamma.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, [e-mail].
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice 
 * is preserved.
 * ====================================================
 */

/* 
 * wrapper float gammaf_r(float x, int *signgamp)
 */

#include "fdlibm.h"

#ifdef _LIBM_REENT
#define gammaf_r _gammaf_r_r
#endif

#if defined (_LIBM_REENT) || ! defined (_REENT_ONLY)

#ifdef __STDC__
	float gammaf_r(_R1 float x, int *signgamp) /* wrapper lgammaf_r */
#else
	float gammaf_r(_R2 x,signgamp)              /* wrapper lgammaf_r */
	_R3 float x; int *signgamp;
#endif
{
#ifdef _IEEE_LIBM
	return __ieee754_gammaf_r(x,signgamp);
#else
        float y;
        y = __ieee754_gammaf_r(x,signgamp);
        if(_LIB_VERSION == _IEEE_) return y;
        if(!finitef(y)&&finitef(x)) {
            if(floorf(x)==x&&x<=(float)0.0)
	        /* gammaf pole */
                return (float)__kernel_standard(_R4,(double)x,(double)x,141);
            else
	        /* gamma overflow */
                return (float)__kernel_standard(_R4,(double)x,(double)x,140);
        } else
            return y;
#endif
}             

#endif /* defined (_LIBM_REENT) || ! defined (_REENT_ONLY) */