e_coshf.c revision 152352
12116Sjkh/* e_coshf.c -- float version of e_cosh.c. 22116Sjkh * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 32116Sjkh */ 42116Sjkh 52116Sjkh/* 62116Sjkh * ==================================================== 72116Sjkh * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 82116Sjkh * 92116Sjkh * Developed at SunPro, a Sun Microsystems, Inc. business. 102116Sjkh * Permission to use, copy, modify, and distribute this 118870Srgrimes * software is freely granted, provided that this notice 122116Sjkh * is preserved. 132116Sjkh * ==================================================== 142116Sjkh */ 152116Sjkh 162116Sjkh#ifndef lint 1750476Speterstatic char rcsid[] = "$FreeBSD: head/lib/msun/src/e_coshf.c 152352 2005-11-13 00:08:23Z bde $"; 182116Sjkh#endif 192116Sjkh 202116Sjkh#include "math.h" 212116Sjkh#include "math_private.h" 222116Sjkh 232116Sjkhstatic const float one = 1.0, half=0.5, huge = 1.0e30; 242116Sjkh 2597407Salfredfloat 2697407Salfred__ieee754_coshf(float x) 278870Srgrimes{ 282116Sjkh float t,w; 292116Sjkh int32_t ix; 302116Sjkh 312116Sjkh GET_FLOAT_WORD(ix,x); 322116Sjkh ix &= 0x7fffffff; 332116Sjkh 342116Sjkh /* x is INF or NaN */ 358870Srgrimes if(ix>=0x7f800000) return x*x; 362116Sjkh 372116Sjkh /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 382116Sjkh if(ix<0x3eb17218) { 392116Sjkh t = expm1f(fabsf(x)); 402116Sjkh w = one+t; 41152352Sbde if (ix<0x39800000) return one; /* cosh(tiny) = 1 */ 422116Sjkh return one+(t*t)/(w+w); 432116Sjkh } 442116Sjkh 45152352Sbde /* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */ 46152352Sbde if (ix < 0x41100000) { 472116Sjkh t = __ieee754_expf(fabsf(x)); 482116Sjkh return half*t+half/t; 492116Sjkh } 502116Sjkh 51152352Sbde /* |x| in [9, log(maxfloat)] return half*exp(|x|) */ 52152352Sbde if (ix < 0x42b17217) return half*__ieee754_expf(fabsf(x)); 532116Sjkh 54152352Sbde /* |x| in [log(maxfloat), overflowthresold] */ 552116Sjkh if (ix<=0x42b2d4fc) { 562116Sjkh w = __ieee754_expf(half*fabsf(x)); 572116Sjkh t = half*w; 582116Sjkh return t*w; 592116Sjkh } 602116Sjkh 612116Sjkh /* |x| > overflowthresold, cosh(x) overflow */ 622116Sjkh return huge*huge; 632116Sjkh} 64