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