1 /* s_tanhf.c -- float version of s_tanh.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
4 * $FreeBSD: src/lib/msun/src/s_tanhf.c,v 1.5 1999/08/28 00:06:56 peter Exp $
5 * $DragonFly: src/lib/msun/src/Attic/s_tanhf.c,v 1.2 2003/06/17 04:26:53 dillon Exp $
9 * ====================================================
10 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
12 * Developed at SunPro, a Sun Microsystems, Inc. business.
13 * Permission to use, copy, modify, and distribute this
14 * software is freely granted, provided that this notice
16 * ====================================================
20 #include "math_private.h"
23 static const float one=1.0, two=2.0, tiny = 1.0e-30;
25 static float one=1.0, two=2.0, tiny = 1.0e-30;
43 if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */
44 else return one/x-one; /* tanh(NaN) = NaN */
48 if (ix < 0x41b00000) { /* |x|<22 */
49 if (ix<0x24000000) /* |x|<2**-55 */
50 return x*(one+x); /* tanh(small) = small */
51 if (ix>=0x3f800000) { /* |x|>=1 */
52 t = expm1f(two*fabsf(x));
53 z = one - two/(t+two);
55 t = expm1f(-two*fabsf(x));
58 /* |x| > 22, return +-1 */
60 z = one - tiny; /* raised inexact flag */
62 return (jx>=0)? z: -z;