e_coshf.c revision 50476
168651Skris/* e_coshf.c -- float version of e_cosh.c. 268651Skris * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 368651Skris */ 468651Skris 568651Skris/* 668651Skris * ==================================================== 768651Skris * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 868651Skris * 968651Skris * Developed at SunPro, a Sun Microsystems, Inc. business. 1068651Skris * Permission to use, copy, modify, and distribute this 1168651Skris * software is freely granted, provided that this notice 1268651Skris * is preserved. 1368651Skris * ==================================================== 1468651Skris */ 1568651Skris 1668651Skris#ifndef lint 1768651Skrisstatic char rcsid[] = "$FreeBSD: head/lib/msun/src/e_coshf.c 50476 1999-08-28 00:22:10Z peter $"; 1868651Skris#endif 1968651Skris 2068651Skris#include "math.h" 2168651Skris#include "math_private.h" 2268651Skris 2368651Skris#ifdef __STDC__ 2468651Skrisstatic const float one = 1.0, half=0.5, huge = 1.0e30; 2568651Skris#else 2668651Skrisstatic float one = 1.0, half=0.5, huge = 1.0e30; 2768651Skris#endif 2868651Skris 2968651Skris#ifdef __STDC__ 3068651Skris float __ieee754_coshf(float x) 3168651Skris#else 3268651Skris float __ieee754_coshf(x) 3368651Skris float x; 3468651Skris#endif 3568651Skris{ 3668651Skris float t,w; 3768651Skris int32_t ix; 3868651Skris 3968651Skris GET_FLOAT_WORD(ix,x); 4068651Skris ix &= 0x7fffffff; 4168651Skris 4268651Skris /* x is INF or NaN */ 4368651Skris if(ix>=0x7f800000) return x*x; 4468651Skris 4568651Skris /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 4668651Skris if(ix<0x3eb17218) { 4768651Skris t = expm1f(fabsf(x)); 4868651Skris w = one+t; 4968651Skris if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ 5068651Skris return one+(t*t)/(w+w); 5168651Skris } 5268651Skris 5368651Skris /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ 5468651Skris if (ix < 0x41b00000) { 5568651Skris t = __ieee754_expf(fabsf(x)); 5668651Skris return half*t+half/t; 5768651Skris } 5868651Skris 5968651Skris /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ 6068651Skris if (ix < 0x42b17180) return half*__ieee754_expf(fabsf(x)); 6168651Skris 6268651Skris /* |x| in [log(maxdouble), overflowthresold] */ 6368651Skris if (ix<=0x42b2d4fc) { 6468651Skris w = __ieee754_expf(half*fabsf(x)); 6568651Skris t = half*w; 6668651Skris return t*w; 6768651Skris } 6868651Skris 6968651Skris /* |x| > overflowthresold, cosh(x) overflow */ 7068651Skris return huge*huge; 7168651Skris} 7268651Skris