RTAI API: base/math/w_exp.c Source File

00001 /* @(#)w_exp.c 5.1 93/09/24 */
00002 /*
00003  * ====================================================
00004  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
00005  *
00006  * Developed at SunPro, a Sun Microsystems, Inc. business.
00007  * Permission to use, copy, modify, and distribute this
00008  * software is freely granted, provided that this notice 
00009  * is preserved.
00010  * ====================================================
00011  */
00012 
00013 #if defined(LIBM_SCCS) && !defined(lint)
00014 static char rcsid[] = "$NetBSD: w_exp.c,v 1.6 1995/05/10 20:48:51 jtc Exp $";
00015 #endif
00016 
00017 /* 
00018  * wrapper exp(x)
00019  */
00020 
00021 #include "math.h"
00022 #include "mathP.h"
00023 
00024 #ifdef __STDC__
00025 static const double
00026 #else
00027 static double
00028 #endif
00029 o_threshold=  7.09782712893383973096e+02,  /* 0x40862E42, 0xFEFA39EF */
00030 u_threshold= -7.45133219101941108420e+02;  /* 0xc0874910, 0xD52D3051 */
00031 
00032 #ifdef __STDC__
00033     double exp(double x)        /* wrapper exp */
00034 #else
00035     double exp(x)           /* wrapper exp */
00036     double x;
00037 #endif
00038 {
00039 #ifdef _IEEE_LIBM
00040     return __ieee754_exp(x);
00041 #else
00042     double z;
00043     z = __ieee754_exp(x);
00044     if(_LIB_VERSION == _IEEE_) return z;
00045     if(finite(x)) {
00046         if(x>o_threshold)
00047             return __kernel_standard(x,x,6); /* exp overflow */
00048         else if(x<u_threshold)
00049             return __kernel_standard(x,x,7); /* exp underflow */
00050     } 
00051     return z;
00052 #endif
00053 }