57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/* s_tanhf.c -- float version of s_tanh.c.
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#include "cdefs-compat.h"
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//__FBSDID("$FreeBSD: src/lib/msun/src/s_tanhf.c,v 1.9 2008/02/22 02:30:36 das Exp $");
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#include <openlibm_math.h>
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#include "math_private.h"
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static const float one=1.0, two=2.0, tiny = 1.0e-30, huge = 1.0e30;
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OLM_DLLEXPORT float
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tanhf(float x)
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{
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float t,z;
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int32_t jx,ix;
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GET_FLOAT_WORD(jx,x);
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ix = jx&0x7fffffff;
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/* x is INF or NaN */
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if(ix>=0x7f800000) {
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if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */
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else return one/x-one; /* tanh(NaN) = NaN */
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}
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/* |x| < 9 */
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if (ix < 0x41100000) { /* |x|<9 */
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if (ix<0x39800000) { /* |x|<2**-12 */
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if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */
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}
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if (ix>=0x3f800000) { /* |x|>=1 */
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t = expm1f(two*fabsf(x));
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z = one - two/(t+two);
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} else {
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t = expm1f(-two*fabsf(x));
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z= -t/(t+two);
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}
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/* |x| >= 9, return +-1 */
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} else {
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z = one - tiny; /* raise inexact flag */
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}
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return (jx>=0)? z: -z;
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}
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