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 #if defined(LIBM_SCCS) && !defined(lint) 14 static char rcsid[] = "$Id: w_exp.c,v 1.5 1994/09/22 16:45:32 jtc Exp $"; 15 #endif 16 17 /* 18 * wrapper exp(x) 19 */ 20 21 #include "math.h" 22 #include "math_private.h" 23 24 #ifdef __STDC__ 25 static const double 26 #else 27 static double 28 #endif 29 o_threshold= 7.09782712893383973096e+02, /* 0x40862E42, 0xFEFA39EF */ 30 u_threshold= -7.45133219101941108420e+02; /* 0xc0874910, 0xD52D3051 */ 31 32 #ifdef __STDC__ 33 double exp(double x) /* wrapper exp */ 34 #else 35 double exp(x) /* wrapper exp */ 36 double x; 37 #endif 38 { 39 #ifdef _IEEE_LIBM 40 return __ieee754_exp(x); 41 #else 42 double z; 43 z = __ieee754_exp(x); 44 if(_LIB_VERSION == _IEEE_) return z; 45 if(finite(x)) { 46 if(x>o_threshold) 47 return __kernel_standard(x,x,6); /* exp overflow */ 48 else if(x<u_threshold) 49 return __kernel_standard(x,x,7); /* exp underflow */ 50 } 51 return z; 52 #endif 53 } 54