e_coshf.c revision 8870
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 178870Srgrimesstatic char rcsid[] = "$Id: e_coshf.c,v 1.1.1.1 1994/08/19 09:39:54 jkh Exp $"; 182116Sjkh#endif 192116Sjkh 202116Sjkh#include "math.h" 212116Sjkh#include "math_private.h" 222116Sjkh 232116Sjkh#ifdef __STDC__ 242116Sjkhstatic const float one = 1.0, half=0.5, huge = 1.0e30; 252116Sjkh#else 262116Sjkhstatic float one = 1.0, half=0.5, huge = 1.0e30; 272116Sjkh#endif 282116Sjkh 292116Sjkh#ifdef __STDC__ 302116Sjkh float __ieee754_coshf(float x) 312116Sjkh#else 322116Sjkh float __ieee754_coshf(x) 332116Sjkh float x; 342116Sjkh#endif 358870Srgrimes{ 362116Sjkh float t,w; 372116Sjkh int32_t ix; 382116Sjkh 392116Sjkh GET_FLOAT_WORD(ix,x); 402116Sjkh ix &= 0x7fffffff; 412116Sjkh 422116Sjkh /* x is INF or NaN */ 438870Srgrimes if(ix>=0x7f800000) return x*x; 442116Sjkh 452116Sjkh /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 462116Sjkh if(ix<0x3eb17218) { 472116Sjkh t = expm1f(fabsf(x)); 482116Sjkh w = one+t; 492116Sjkh if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ 502116Sjkh return one+(t*t)/(w+w); 512116Sjkh } 522116Sjkh 532116Sjkh /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ 542116Sjkh if (ix < 0x41b00000) { 552116Sjkh t = __ieee754_expf(fabsf(x)); 562116Sjkh return half*t+half/t; 572116Sjkh } 582116Sjkh 592116Sjkh /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ 602116Sjkh if (ix < 0x42b17180) return half*__ieee754_expf(fabsf(x)); 612116Sjkh 622116Sjkh /* |x| in [log(maxdouble), overflowthresold] */ 632116Sjkh if (ix<=0x42b2d4fc) { 642116Sjkh w = __ieee754_expf(half*fabsf(x)); 652116Sjkh t = half*w; 662116Sjkh return t*w; 672116Sjkh } 682116Sjkh 692116Sjkh /* |x| > overflowthresold, cosh(x) overflow */ 702116Sjkh return huge*huge; 712116Sjkh} 72