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)
17static char rcsid[] = "$NetBSD: e_coshf.c,v 1.6 1996/04/08 15:43:41 phil Exp $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23#ifdef __STDC__
24static const float huge = 1.0e30;
25static const float one = 1.0, half=0.5;
26#else
27static float one = 1.0, half=0.5, huge = 1.0e30;
28#endif
29
30#ifdef __STDC__
31	float __ieee754_coshf(float x)
32#else
33	float __ieee754_coshf(x)
34	float x;
35#endif
36{
37	float t,w;
38	int32_t ix;
39
40	GET_FLOAT_WORD(ix,x);
41	ix &= 0x7fffffff;
42
43    /* x is INF or NaN */
44	if(ix>=0x7f800000) return x*x;
45
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);
52	}
53
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;
58	}
59
60    /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
61	if (ix < 0x42b17180)  return half*__ieee754_expf(fabsf(x));
62
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;
68	}
69
70    /* |x| > overflowthresold, cosh(x) overflow */
71	return huge*huge;
72}
73