| 0,0 → 1,65 |
|---|
| /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
| /* 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[] = "$Id: s_tanhf.c,v 1.2 1994/08/18 23:10:23 jtc 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; |
| } |