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 #if defined(LIBM_SCCS) && !defined(lint) 17 static char rcsid[] = "$NetBSD: e_coshf.c,v 1.5 1995/05/10 20:45:01 jtc Exp $"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 static const volatile float huge = 1.0e30; 24 static const float one = 1.0, half=0.5; 25 26 float 27 coshf(float x) 28 { 29 float t,w; 30 int32_t ix; 31 32 GET_FLOAT_WORD(ix,x); 33 ix &= 0x7fffffff; 34 35 /* x is INF or NaN */ 36 if(ix>=0x7f800000) return x*x; 37 38 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 39 if(ix<0x3eb17218) { 40 t = expm1f(fabsf(x)); 41 w = one+t; 42 if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ 43 return one+(t*t)/(w+w); 44 } 45 46 /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ 47 if (ix < 0x41b00000) { 48 t = expf(fabsf(x)); 49 return half*t+half/t; 50 } 51 52 /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ 53 if (ix < 0x42b17180) return half*expf(fabsf(x)); 54 55 /* |x| in [log(maxdouble), overflowthresold] */ 56 if (ix<=0x42b2d4fc) { 57 w = expf(half*fabsf(x)); 58 t = half*w; 59 return t*w; 60 } 61 62 /* |x| > overflowthresold, cosh(x) overflow */ 63 return huge*huge; 64 } 65