mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-16 20:02:35 +03:00
74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
/* sf_tanh.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 "fdlibm.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(!FLT_UWORD_IS_FINITE(ix)) {
|
|
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;
|
|
}
|
|
|
|
#ifdef _DOUBLE_IS_32BITS
|
|
|
|
#ifdef __STDC__
|
|
double tanh(double x)
|
|
#else
|
|
double tanh(x)
|
|
double x;
|
|
#endif
|
|
{
|
|
return (double) tanhf((float) x);
|
|
}
|
|
|
|
#endif /* defined(_DOUBLE_IS_32BITS) */
|