1 /* ef_cosh.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 "fdlibm.h"
17 #include "math_config.h"
18
19 #ifdef __v810__
20 #define const
21 #endif
22
23 static const float one = 1.0, half = 0.5;
24
25 float
coshf(float x)26 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 = fabsf(x);
35
36 /* x is INF or NaN */
37 if (!FLT_UWORD_IS_FINITE(ix))
38 return x + x;
39
40 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
41 if (ix < 0x3eb17218) {
42 t = expm1f(x);
43 w = one + t;
44 if (ix < 0x24000000)
45 return w; /* cosh(tiny) = 1 */
46 return one + (t * t) / (w + w);
47 }
48
49 /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
50 if (ix < 0x41b00000) {
51 t = expf(x);
52 return half * t + half / t;
53 }
54
55 /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
56 if (ix <= FLT_UWORD_LOG_MAX)
57 return half * expf(x);
58
59 /* |x| in [log(maxdouble), overflowthresold] */
60 if (ix <= FLT_UWORD_LOG_2MAX) {
61 w = expf(half * x);
62 t = half * w;
63 return t * w;
64 }
65
66 /* |x| > overflowthresold, cosh(x) overflow */
67 return __math_oflowf(0);
68 }
69
70 _MATH_ALIAS_f_f(cosh)
71
