1 /* @(#)w_gamma.c 5.1 93/09/24 */ 2 /* 3 * ==================================================== 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5 * 6 * Developed at SunPro, a Sun Microsystems, Inc. business. 7 * Permission to use, copy, modify, and distribute this 8 * software is freely granted, provided that this notice 9 * is preserved. 10 * ==================================================== 11 */ 12 13 #include <sys/cdefs.h> 14 #if defined(LIBM_SCCS) && !defined(lint) 15 __RCSID("$NetBSD: w_gamma.c,v 1.8 1997/10/09 11:34:48 lukem Exp $"); 16 #endif 17 18 /* double gamma(double x) 19 * Return the logarithm of the Gamma function of x. 20 * 21 * Method: call gamma_r 22 */ 23 24 #include "math.h" 25 #include "math_private.h" 26 27 extern int signgam; 28 29 #ifdef __STDC__ 30 double gamma(double x) 31 #else 32 double gamma(x) 33 double x; 34 #endif 35 { 36 #ifdef _IEEE_LIBM 37 return __ieee754_lgamma_r(x,&signgam); 38 #else 39 double y; 40 y = __ieee754_lgamma_r(x,&signgam); 41 if(_LIB_VERSION == _IEEE_) return y; 42 if(!finite(y)&&finite(x)) { 43 if(floor(x)==x&&x<=0.0) 44 return __kernel_standard(x,x,41); /* gamma pole */ 45 else 46 return __kernel_standard(x,x,40); /* gamma overflow */ 47 } else 48 return y; 49 #endif 50 } 51