RTAI API: base/math/w_gamma.c Source File

00001 /* @(#)w_gamma.c 5.1 93/09/24 */ 00002 /* 00003 * ==================================================== 00004 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 00005 * 00006 * Developed at SunPro, a Sun Microsystems, Inc. business. 00007 * Permission to use, copy, modify, and distribute this 00008 * software is freely granted, provided that this notice 00009 * is preserved. 00010 * ==================================================== 00011 */ 00012 00013 #if defined(LIBM_SCCS) && !defined(lint) 00014 static char rcsid[] = "$NetBSD: w_gamma.c,v 1.7 1995/11/20 22:06:43 jtc Exp $"; 00015 #endif 00016 00017 /* double gamma(double x) 00018 * Return the logarithm of the Gamma function of x. 00019 * 00020 * Method: call gamma_r 00021 */ 00022 00023 #include "math.h" 00024 #include "mathP.h" 00025 00026 extern int signgam; 00027 00028 #ifdef __STDC__ 00029 double gamma(double x) 00030 #else 00031 double gamma(x) 00032 double x; 00033 #endif 00034 { 00035 #ifdef _IEEE_LIBM 00036 return __ieee754_lgamma_r(x,&signgam); 00037 #else 00038 double y; 00039 y = __ieee754_lgamma_r(x,&signgam); 00040 if(_LIB_VERSION == _IEEE_) return y; 00041 if(!finite(y)&&finite(x)) { 00042 if(floor(x)==x&&x<=0.0) 00043 return __kernel_standard(x,x,41); /* gamma pole */ 00044 else 00045 return __kernel_standard(x,x,40); /* gamma overflow */ 00046 } else 00047 return y; 00048 #endif 00049 }