| /* 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. |
| * ==================================================== |
| */ |
| |
| #if defined(LIBM_SCCS) && !defined(lint) |
| static char rcsid[] = "$NetBSD: s_tanhf.c,v 1.4 1995/05/10 20:48:24 jtc Exp $"; |
| #endif |
| |
| #include <float.h> |
| #include <math.h> |
| #include <math_private.h> |
| #include <libm-alias-float.h> |
| |
| static const float one=1.0, two=2.0, tiny = 1.0e-30; |
| |
| float __tanhf(float x) |
| { |
| 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 == 0) |
| return x; /* x == +-0 */ |
| if (ix<0x24000000) /* |x|<2**-55 */ |
| { |
| math_check_force_underflow (x); |
| 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; |
| } |
| libm_alias_float (__tanh, tanh) |
