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 1.8 1999/07/02 15:37:38 simonb Exp $");
19#endif
20
21#include "math.h"
22#include "math_private.h"
23
24static const float huge = 1.0e30;
25static const float one = 1.0, half=0.5;
26
27float
28__ieee754_coshf(float x)
29{
30	float t,w;
31	int32_t ix;
32
33	GET_FLOAT_WORD(ix,x);
34	ix &= 0x7fffffff;
35
36    /* x is INF or NaN */
37	if(ix>=0x7f800000) return x*x;
38
39    /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
40	if(ix<0x3eb17218) {
41	    t = expm1f(fabsf(x));
42	    w = one+t;
43	    if (ix<0x24000000) return w;	/* cosh(tiny) = 1 */
44	    return one+(t*t)/(w+w);
45	}
46
47    /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
48	if (ix < 0x41b00000) {
49		t = __ieee754_expf(fabsf(x));
50		return half*t+half/t;
51	}
52
53    /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
54	if (ix < 0x42b17180)  return half*__ieee754_expf(fabsf(x));
55
56    /* |x| in [log(maxdouble), overflowthresold] */
57	if (ix<=0x42b2d4fc) {
58	    w = __ieee754_expf(half*fabsf(x));
59	    t = half*w;
60	    return t*w;
61	}
62
63    /* |x| > overflowthresold, cosh(x) overflow */
64	return huge*huge;
65}
66