1 /* e_coshf.c -- float version of e_cosh.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian (at) cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #ifndef lint 17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_coshf.c,v 1.7 2005/11/13 00:08:23 bde Exp $"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 static const float one = 1.0, half=0.5, huge = 1.0e30; 24 25 float 26 __ieee754_coshf(float x) 27 { 28 float t,w; 29 int32_t ix; 30 31 GET_FLOAT_WORD(ix,x); 32 ix &= 0x7fffffff; 33 34 /* x is INF or NaN */ 35 if(ix>=0x7f800000) return x*x; 36 37 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 38 if(ix<0x3eb17218) { 39 t = expm1f(fabsf(x)); 40 w = one+t; 41 if (ix<0x39800000) return one; /* cosh(tiny) = 1 */ 42 return one+(t*t)/(w+w); 43 } 44 45 /* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */ 46 if (ix < 0x41100000) { 47 t = __ieee754_expf(fabsf(x)); 48 return half*t+half/t; 49 } 50 51 /* |x| in [9, log(maxfloat)] return half*exp(|x|) */ 52 if (ix < 0x42b17217) return half*__ieee754_expf(fabsf(x)); 53 54 /* |x| in [log(maxfloat), overflowthresold] */ 55 if (ix<=0x42b2d4fc) { 56 w = __ieee754_expf(half*fabsf(x)); 57 t = half*w; 58 return t*w; 59 } 60 61 /* |x| > overflowthresold, cosh(x) overflow */ 62 return huge*huge; 63 } 64
