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/* origin: FreeBSD /usr/src/lib/msun/src/s_tanhf.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 "libm.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 */
}
if (ix < 0x41100000) { /* |x| < 9 */
if (ix < 0x39800000) { /* |x| < 2**-12 */
/* tanh(tiny) = tiny with inexact */
if (huge+x > one)
return x;
}
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);
}
} else { /* |x| >= 9, return +-1 */
z = one - tiny; /* raise inexact */
}
return jx >= 0 ? z : -z;
}
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