1/* e_acoshf.c -- float version of e_acosh.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#if defined(LIBM_SCCS) && !defined(lint)
17static char rcsid[] = "$NetBSD: e_acoshf.c,v 1.5 1995/05/12 04:57:20 jtc Exp $";
18#endif
19
20#include <math.h>
21#include <math_private.h>
22#include <libm-alias-finite.h>
23
24static const float
25one = 1.0,
26ln2 = 6.9314718246e-01; /* 0x3f317218 */
27
28float __ieee754_acoshf(float x)
29{
30 float t;
31 int32_t hx;
32 GET_FLOAT_WORD(hx,x);
33 if(hx<0x3f800000) { /* x < 1 */
34 return (x-x)/(x-x);
35 } else if(hx >=0x4d800000) { /* x > 2**28 */
36 if(hx >=0x7f800000) { /* x is inf of NaN */
37 return x+x;
38 } else
39 return __ieee754_logf(x)+ln2; /* acosh(huge)=log(2x) */
40 } else if (hx==0x3f800000) {
41 return 0.0; /* acosh(1) = 0 */
42 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
43 t=x*x;
44 return __ieee754_logf((float)2.0*x-one/(x+sqrtf(t-one)));
45 } else { /* 1<x<2 */
46 t = x-one;
47 return __log1pf(t+sqrtf((float)2.0*t+t*t));
48 }
49}
50libm_alias_finite (__ieee754_acoshf, __acoshf)
51