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 * ====================================================
17 static char rcsid[] = "$Id: e_acoshf.c,v 1.4 1997/02/22 15:09:56 peter Exp $";
21 #include "math_private.h"
29 ln2 = 6.9314718246e-01; /* 0x3f317218 */
32 float __ieee754_acoshf(float x)
34 float __ieee754_acoshf(x)
41 if(hx<0x3f800000) { /* x < 1 */
43 } else if(hx >=0x4d800000) { /* x > 2**28 */
44 if(hx >=0x7f800000) { /* x is inf of NaN */
47 return __ieee754_logf(x)+ln2; /* acosh(huge)=log(2x) */
48 } else if (hx==0x3f800000) {
49 return 0.0; /* acosh(1) = 0 */
50 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
52 return __ieee754_logf((float)2.0*x-one/(x+__ieee754_sqrtf(t-one)));
55 return log1pf(t+__ieee754_sqrtf((float)2.0*t+t*t));