| /* 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. |
| * ==================================================== |
| */ |
| |
| #include <sys/cdefs.h> |
| __FBSDID("$FreeBSD$"); |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| static const float one=1.0, two=2.0, tiny = 1.0e-30, huge = 1.0e30; |
| 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| < 9 */ |
| if (ix < 0x41100000) { /* |x|<9 */ |
| if (ix<0x39800000) { /* |x|<2**-12 */ |
| if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */ |
| } |
| 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| >= 9, return +-1 */ |
| } else { |
| z = one - tiny; /* raise inexact flag */ |
| } |
| return (jx>=0)? z: -z; |
| } |
