author | Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com> |
Fri, 11 Jun 2010 15:26:22 +0300 | |
changeset 34 | 5fae379060a7 |
parent 0 | e4d67989cc36 |
permissions | -rw-r--r-- |
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/*-------------------------------------------------------------------- |
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*© Portions copyright (c) 2006 Nokia Corporation. All rights reserved. |
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*-------------------------------------------------------------------- |
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*/ |
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/* 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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#ifndef __SYMBIAN32__ |
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#ifndef lint |
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static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_tanhf.c,v 1.7 2002/05/28 18:15:04 alfred Exp $"; |
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#endif |
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#endif //__SYMBIAN32__ |
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#include <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; |
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EXPORT_C 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| < 22 */ |
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if (ix < 0x41b00000) { /* |x|<22 */ |
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if (ix<0x24000000) /* |x|<2**-55 */ |
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return x*(one+x); /* tanh(small) = small */ |
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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| > 22, return +-1 */ |
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} else { |
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z = one - tiny; /* raised inexact flag */ |
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} |
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return (jx>=0)? z: -z; |
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} |