1*05a0b428SJohn Marino /* e_atanhf.c -- float version of e_atanh.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 one = 1.0, huge = 1e30;
20*05a0b428SJohn Marino static const float zero = 0.0;
21*05a0b428SJohn Marino
22*05a0b428SJohn Marino float
atanhf(float x)23*05a0b428SJohn Marino atanhf(float x)
24*05a0b428SJohn Marino {
25*05a0b428SJohn Marino float t;
26*05a0b428SJohn Marino int32_t hx,ix;
27*05a0b428SJohn Marino GET_FLOAT_WORD(hx,x);
28*05a0b428SJohn Marino ix = hx&0x7fffffff;
29*05a0b428SJohn Marino if (ix>0x3f800000) /* |x|>1 */
30*05a0b428SJohn Marino return (x-x)/(x-x);
31*05a0b428SJohn Marino if(ix==0x3f800000)
32*05a0b428SJohn Marino return x/zero;
33*05a0b428SJohn Marino if(ix<0x31800000&&(huge+x)>zero) return x; /* x<2**-28 */
34*05a0b428SJohn Marino SET_FLOAT_WORD(x,ix);
35*05a0b428SJohn Marino if(ix<0x3f000000) { /* x < 0.5 */
36*05a0b428SJohn Marino t = x+x;
37*05a0b428SJohn Marino t = (float)0.5*log1pf(t+t*x/(one-x));
38*05a0b428SJohn Marino } else
39*05a0b428SJohn Marino t = (float)0.5*log1pf((x+x)/(one-x));
40*05a0b428SJohn Marino if(hx>=0) return t; else return -t;
41*05a0b428SJohn Marino }
42