1 /* e_acoshf.c -- float version of e_acosh.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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
13 * ====================================================
15 * $NetBSD: e_acoshf.c,v 1.8 2002/05/26 22:01:48 wiz Exp $
16 * $DragonFly: src/lib/libm/src/e_acoshf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
20 #include "math_private.h"
24 ln2
= 6.9314718246e-01; /* 0x3f317218 */
32 if(hx
<0x3f800000) { /* x < 1 */
34 } else if(hx
>=0x4d800000) { /* x > 2**28 */
35 if(hx
>=0x7f800000) { /* x is inf of NaN */
38 return 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 */
43 return logf((float)2.0*x
-one
/(x
+sqrtf(t
-one
)));
46 return log1pf(t
+sqrtf((float)2.0*t
+t
*t
));