w_exp.c (1146B)
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[] = "$FreeBSD: src/lib/msun/src/w_exp.c,v 1.7 2002/05/28 18:15:04 alfred Exp $"; 15 #endif 16 17 /* 18 * wrapper exp(x) 19 */ 20 21 #include "math.h" 22 #include "math_private.h" 23 24 static const double 25 o_threshold= 7.09782712893383973096e+02, /* 0x40862E42, 0xFEFA39EF */ 26 u_threshold= -7.45133219101941108420e+02; /* 0xc0874910, 0xD52D3051 */ 27 28 double 29 exp(double x) /* wrapper exp */ 30 { 31 #ifdef _IEEE_LIBM 32 return __ieee754_exp(x); 33 #else 34 double z; 35 z = __ieee754_exp(x); 36 if(_LIB_VERSION == _IEEE_) return z; 37 if(finite(x)) { 38 if(x>o_threshold) 39 return __kernel_standard(x,x,6); /* exp overflow */ 40 else if(x<u_threshold) 41 return __kernel_standard(x,x,7); /* exp underflow */ 42 } 43 return z; 44 #endif 45 }