Update.
[glibc.git] / sysdeps / libm-ieee754 / e_coshf.c
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1 /* e_coshf.c -- float version of e_cosh.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
5 /*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 * ====================================================
16 #if defined(LIBM_SCCS) && !defined(lint)
17 static char rcsid[] = "$NetBSD: e_coshf.c,v 1.6 1996/04/08 15:43:41 phil Exp $";
18 #endif
20 #include "math.h"
21 #include "math_private.h"
23 #ifdef __STDC__
24 static const float huge = 1.0e30;
25 static const float one = 1.0, half=0.5;
26 #else
27 static float one = 1.0, half=0.5, huge = 1.0e30;
28 #endif
30 #ifdef __STDC__
31 float __ieee754_coshf(float x)
32 #else
33 float __ieee754_coshf(x)
34 float x;
35 #endif
37 float t,w;
38 int32_t ix;
40 GET_FLOAT_WORD(ix,x);
41 ix &= 0x7fffffff;
43 /* x is INF or NaN */
44 if(ix>=0x7f800000) return x*x;
46 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
47 if(ix<0x3eb17218) {
48 t = __expm1f(fabsf(x));
49 w = one+t;
50 if (ix<0x24000000) return w; /* cosh(tiny) = 1 */
51 return one+(t*t)/(w+w);
54 /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
55 if (ix < 0x41b00000) {
56 t = __ieee754_expf(fabsf(x));
57 return half*t+half/t;
60 /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
61 if (ix < 0x42b17180) return half*__ieee754_expf(fabsf(x));
63 /* |x| in [log(maxdouble), overflowthresold] */
64 if (ix<=0x42b2d4fc) {
65 w = __ieee754_expf(half*fabsf(x));
66 t = half*w;
67 return t*w;
70 /* |x| > overflowthresold, cosh(x) overflow */
71 return huge*huge;