1/* e_coshf.c -- float version of e_cosh.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 * Optimizations by Ulrich Drepper <drepper@gmail.com>, 2011
4 */
5
6/*
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 *
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
13 * is preserved.
14 * ====================================================
15 */
16
17#include <math.h>
18#include <math-narrow-eval.h>
19#include <math_private.h>
20#include <libm-alias-finite.h>
21
22static const float huge = 1.0e30;
23static const float one = 1.0, half=0.5;
24
25float
26__ieee754_coshf (float x)
27{
28 float t,w;
29 int32_t ix;
30
31 GET_FLOAT_WORD(ix,x);
32 ix &= 0x7fffffff;
33
34 /* |x| in [0,22] */
35 if (ix < 0x41b00000) {
36 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
37 if(ix<0x3eb17218) {
38 if (ix<0x24000000) return one; /* cosh(tiny) = 1 */
39 t = __expm1f(fabsf(x));
40 w = one+t;
41 return one+(t*t)/(w+w);
42 }
43
44 /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
45 t = __ieee754_expf(fabsf(x));
46 return half*t+half/t;
47 }
48
49 /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
50 if (ix < 0x42b17180) return half*__ieee754_expf(fabsf(x));
51
52 /* |x| in [log(maxdouble), overflowthresold] */
53 if (ix<=0x42b2d4fc) {
54 w = __ieee754_expf(half*fabsf(x));
55 t = half*w;
56 return t*w;
57 }
58
59 /* x is INF or NaN */
60 if(ix>=0x7f800000) return x*x;
61
62 /* |x| > overflowthresold, cosh(x) overflow */
63 return math_narrow_eval (huge*huge);
64}
65libm_alias_finite (__ieee754_coshf, __coshf)
66