1 /* s_tanhf.c -- float version of s_tanh.c.
2 * 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 * ====================================================
15 * $FreeBSD: head/lib/msun/src/s_tanhf.c 176451 2008-02-22 02:30:36Z das $
19 #include "math_private.h"
21 static const float one=1.0, two=2.0, tiny = 1.0e-30, huge = 1.0e30;
33 if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */
34 else return one/x-one; /* tanh(NaN) = NaN */
38 if (ix < 0x41100000) { /* |x|<9 */
39 if (ix<0x39800000) { /* |x|<2**-12 */
40 if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */
42 if (ix>=0x3f800000) { /* |x|>=1 */
43 t = expm1f(two*fabsf(x));
44 z = one - two/(t+two);
46 t = expm1f(-two*fabsf(x));
49 /* |x| >= 9, return +-1 */
51 z = one - tiny; /* raise inexact flag */
53 return (jx>=0)? z: -z;