/* s_tanhf.c -- float version of s_tanh.c. * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ #ifndef lint static char rcsid[] = "$Id: s_tanhf.c,v 1.1.1.1 1994/08/19 09:39:59 jkh Exp $"; #endif #include "math.h" #include "math_private.h" #ifdef __STDC__ static const float one=1.0, two=2.0, tiny = 1.0e-30; #else static float one=1.0, two=2.0, tiny = 1.0e-30; #endif #ifdef __STDC__ float tanhf(float x) #else float tanhf(x) float x; #endif { float t,z; int32_t jx,ix; GET_FLOAT_WORD(jx,x); ix = jx&0x7fffffff; /* x is INF or NaN */ if(ix>=0x7f800000) { if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */ else return one/x-one; /* tanh(NaN) = NaN */ } /* |x| < 22 */ if (ix < 0x41b00000) { /* |x|<22 */ if (ix<0x24000000) /* |x|<2**-55 */ return x*(one+x); /* tanh(small) = small */ if (ix>=0x3f800000) { /* |x|>=1 */ t = expm1f(two*fabsf(x)); z = one - two/(t+two); } else { t = expm1f(-two*fabsf(x)); z= -t/(t+two); } /* |x| > 22, return +-1 */ } else { z = one - tiny; /* raised inexact flag */ } return (jx>=0)? z: -z; }