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 #include <sys/cdefs.h> 14 #if defined(LIBM_SCCS) && !defined(lint) 15 __RCSID("$NetBSD: w_exp.c,v 1.9 2002/05/26 22:02:00 wiz Exp $"); 16 #endif 17 18 /* 19 * wrapper exp(x) 20 */ 21 22 #include "math.h" 23 #include "math_private.h" 24 25 static const double 26 o_threshold= 7.09782712893383973096e+02, /* 0x40862E42, 0xFEFA39EF */ 27 u_threshold= -7.45133219101941108420e+02; /* 0xc0874910, 0xD52D3051 */ 28 29 double 30 exp(double x) /* wrapper exp */ 31 { 32 #ifdef _IEEE_LIBM 33 return __ieee754_exp(x); 34 #else 35 double z; 36 z = __ieee754_exp(x); 37 if(_LIB_VERSION == _IEEE_) return z; 38 if(finite(x)) { 39 if(x>o_threshold) 40 return __kernel_standard(x,x,6); /* exp overflow */ 41 else if(x<u_threshold) 42 return __kernel_standard(x,x,7); /* exp underflow */ 43 } 44 return z; 45 #endif 46 } 47