1 /* e_coshf.c -- float version of e_cosh.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@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 #include <sys/cdefs.h> 17 #if defined(LIBM_SCCS) && !defined(lint) 18 __RCSID("$NetBSD: e_coshf.c,v 1.7 1997/10/09 11:28:51 lukem Exp $"); 19 #endif 20 21 #include "math.h" 22 #include "math_private.h" 23 24 #ifdef __STDC__ 25 static const float huge = 1.0e30; 26 static const float one = 1.0, half=0.5; 27 #else 28 static float one = 1.0, half=0.5, huge = 1.0e30; 29 #endif 30 31 #ifdef __STDC__ 32 float __ieee754_coshf(float x) 33 #else 34 float __ieee754_coshf(x) 35 float x; 36 #endif 37 { 38 float t,w; 39 int32_t ix; 40 41 GET_FLOAT_WORD(ix,x); 42 ix &= 0x7fffffff; 43 44 /* x is INF or NaN */ 45 if(ix>=0x7f800000) return x*x; 46 47 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 48 if(ix<0x3eb17218) { 49 t = expm1f(fabsf(x)); 50 w = one+t; 51 if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ 52 return one+(t*t)/(w+w); 53 } 54 55 /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ 56 if (ix < 0x41b00000) { 57 t = __ieee754_expf(fabsf(x)); 58 return half*t+half/t; 59 } 60 61 /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ 62 if (ix < 0x42b17180) return half*__ieee754_expf(fabsf(x)); 63 64 /* |x| in [log(maxdouble), overflowthresold] */ 65 if (ix<=0x42b2d4fc) { 66 w = __ieee754_expf(half*fabsf(x)); 67 t = half*w; 68 return t*w; 69 } 70 71 /* |x| > overflowthresold, cosh(x) overflow */ 72 return huge*huge; 73 } 74