1*05a0b428SJohn Marino /* e_acoshf.c -- float version of e_acosh.c.
2*05a0b428SJohn Marino * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3*05a0b428SJohn Marino */
4*05a0b428SJohn Marino
5*05a0b428SJohn Marino /*
6*05a0b428SJohn Marino * ====================================================
7*05a0b428SJohn Marino * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8*05a0b428SJohn Marino *
9*05a0b428SJohn Marino * Developed at SunPro, a Sun Microsystems, Inc. business.
10*05a0b428SJohn Marino * Permission to use, copy, modify, and distribute this
11*05a0b428SJohn Marino * software is freely granted, provided that this notice
12*05a0b428SJohn Marino * is preserved.
13*05a0b428SJohn Marino * ====================================================
14*05a0b428SJohn Marino */
15*05a0b428SJohn Marino
16*05a0b428SJohn Marino #include "math.h"
17*05a0b428SJohn Marino #include "math_private.h"
18*05a0b428SJohn Marino
19*05a0b428SJohn Marino static const float
20*05a0b428SJohn Marino one = 1.0,
21*05a0b428SJohn Marino ln2 = 6.9314718246e-01; /* 0x3f317218 */
22*05a0b428SJohn Marino
23*05a0b428SJohn Marino float
acoshf(float x)24*05a0b428SJohn Marino acoshf(float x)
25*05a0b428SJohn Marino {
26*05a0b428SJohn Marino float t;
27*05a0b428SJohn Marino int32_t hx;
28*05a0b428SJohn Marino GET_FLOAT_WORD(hx,x);
29*05a0b428SJohn Marino if(hx<0x3f800000) { /* x < 1 */
30*05a0b428SJohn Marino return (x-x)/(x-x);
31*05a0b428SJohn Marino } else if(hx >=0x4d800000) { /* x > 2**28 */
32*05a0b428SJohn Marino if(hx >=0x7f800000) { /* x is inf of NaN */
33*05a0b428SJohn Marino return x+x;
34*05a0b428SJohn Marino } else
35*05a0b428SJohn Marino return logf(x)+ln2; /* acosh(huge)=log(2x) */
36*05a0b428SJohn Marino } else if (hx==0x3f800000) {
37*05a0b428SJohn Marino return 0.0; /* acosh(1) = 0 */
38*05a0b428SJohn Marino } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
39*05a0b428SJohn Marino t=x*x;
40*05a0b428SJohn Marino return logf((float)2.0*x-one/(x+sqrtf(t-one)));
41*05a0b428SJohn Marino } else { /* 1<x<2 */
42*05a0b428SJohn Marino t = x-one;
43*05a0b428SJohn Marino return log1pf(t+sqrtf((float)2.0*t+t*t));
44*05a0b428SJohn Marino }
45*05a0b428SJohn Marino }
46