1 /* origin: FreeBSD /usr/src/lib/msun/src/e_atanhf.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 * ====================================================
18 static const float one = 1.0, huge = 1e30;
19 static const float zero = 0.0;
26 GET_FLOAT_WORD(hx, x);
28 if (ix > 0x3f800000) /* |x| > 1 */
32 if (ix < 0x31800000 && huge+x > zero) /* x < 2**-28 */
34 SET_FLOAT_WORD(x, ix);
35 if (ix < 0x3f000000) { /* x < 0.5 */
37 t = (float)0.5*log1pf(t + t*x/(one-x));
39 t = (float)0.5*log1pf((x+x)/(one-x));