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 #ifndef lint 14 static char rcsid[] = "$Id: w_gamma.c,v 1.3 1994/02/18 02:27:27 jtc Exp $"; 15 #endif 16 17 /* double gamma(double x) 18 * Return the logarithm of the Gamma function of x. 19 * 20 * Method: call gamma_r 21 */ 22 23 #include <math.h> 24 25 extern int signgam; 26 27 #ifdef __STDC__ 28 double gamma(double x) 29 #else 30 double gamma(x) 31 double x; 32 #endif 33 { 34 #ifdef _IEEE_LIBM 35 return __ieee754_gamma_r(x,&signgam); 36 #else 37 double y; 38 y = __ieee754_gamma_r(x,&signgam); 39 if(_LIB_VERSION == _IEEE_) return y; 40 if(!finite(y)&&finite(x)) { 41 if(floor(x)==x&&x<=0.0) 42 return __kernel_standard(x,x,41); /* gamma pole */ 43 else 44 return __kernel_standard(x,x,40); /* gamma overflow */ 45 } else 46 return y; 47 #endif 48 } 49