1 /* origin: FreeBSD /usr/src/lib/msun/src/e_acoshf.c */
3 * 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 * ====================================================
20 ln2 = 6.9314718246e-01; /* 0x3f317218 */
27 GET_FLOAT_WORD(hx, x);
28 if (hx < 0x3f800000) { /* x < 1 */
30 } else if (hx >= 0x4d800000) { /* x > 2**28 */
31 if (hx >= 0x7f800000) /* x is inf of NaN */
33 return logf(x) + ln2; /* acosh(huge)=log(2x) */
34 } else if (hx == 0x3f800000) {
35 return 0.0; /* acosh(1) = 0 */
36 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
38 return logf(2.0f*x - one/(x+sqrtf(t-one)));
39 } else { /* 1 < x < 2 */
41 return log1pf(t + sqrtf(2.0f*t+t*t));