1/* e_acoshf.c -- float version of e_acosh.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#if defined(LIBM_SCCS) && !defined(lint)
16static char rcsid[] = "$NetBSD: e_acoshf.c,v 1.5 1995/05/12 04:57:20 jtc Exp $";
17#endif
18
19#include <math.h>
20#include <math_private.h>
21#include <libm-alias-finite.h>
22
23static const float
24one = 1.0,
25ln2 = 6.9314718246e-01; /* 0x3f317218 */
26
27float __ieee754_acoshf(float x)
28{
29 float t;
30 int32_t hx;
31 GET_FLOAT_WORD(hx,x);
32 if(hx<0x3f800000) { /* x < 1 */
33 return (x-x)/(x-x);
34 } else if(hx >=0x4d800000) { /* x > 2**28 */
35 if(hx >=0x7f800000) { /* x is inf of NaN */
36 return x+x;
37 } else
38 return __ieee754_logf(x)+ln2; /* acosh(huge)=log(2x) */
39 } else if (hx==0x3f800000) {
40 return 0.0; /* acosh(1) = 0 */
41 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
42 t=x*x;
43 return __ieee754_logf((float)2.0*x-one/(x+sqrtf(t-one)));
44 } else { /* 1<x<2 */
45 t = x-one;
46 return __log1pf(t+sqrtf((float)2.0*t+t*t));
47 }
48}
49libm_alias_finite (__ieee754_acoshf, __acoshf)
50