mirror of
https://git.planet-casio.com/Lephenixnoir/OpenLibm.git
synced 2024-12-28 20:43:41 +01:00
56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/* 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 "cdefs-compat.h"
|
|
//__FBSDID("$FreeBSD: src/lib/msun/src/s_tanhf.c,v 1.9 2008/02/22 02:30:36 das Exp $");
|
|
|
|
#include <openlibm_math.h>
|
|
|
|
#include "math_private.h"
|
|
|
|
static const float one=1.0, two=2.0, tiny = 1.0e-30, huge = 1.0e30;
|
|
OLM_DLLEXPORT 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;
|
|
}
|