1 /* @(#)w_exp.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_exp.c,v 1.3 1994/02/18 02:27:21 jtc Exp $"; 15 #endif 16 17 /* 18 * wrapper exp(x) 19 */ 20 21 #include <math.h> 22 23 #ifdef __STDC__ 24 static const double 25 #else 26 static double 27 #endif 28 o_threshold= 7.09782712893383973096e+02, /* 0x40862E42, 0xFEFA39EF */ 29 u_threshold= -7.45133219101941108420e+02; /* 0xc0874910, 0xD52D3051 */ 30 31 #ifdef __STDC__ 32 double exp(double x) /* wrapper exp */ 33 #else 34 double exp(x) /* wrapper exp */ 35 double x; 36 #endif 37 { 38 #ifdef _IEEE_LIBM 39 return __ieee754_exp(x); 40 #else 41 double z; 42 z = __ieee754_exp(x); 43 if(_LIB_VERSION == _IEEE_) return z; 44 if(finite(x)) { 45 if(x>o_threshold) 46 return __kernel_standard(x,x,6); /* exp overflow */ 47 else if(x<u_threshold) 48 return __kernel_standard(x,x,7); /* exp underflow */ 49 } 50 return z; 51 #endif 52 } 53