152 lines
2.8 KiB
C
152 lines
2.8 KiB
C
/* tanhl.c
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*
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* Hyperbolic tangent, long double precision
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*
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*
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*
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* SYNOPSIS:
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*
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* long double x, y, tanhl();
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*
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* y = tanhl( x );
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*
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*
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*
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* DESCRIPTION:
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*
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* Returns hyperbolic tangent of argument in the range MINLOGL to
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* MAXLOGL.
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*
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* A rational function is used for |x| < 0.625. The form
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* x + x**3 P(x)/Q(x) of Cody _& Waite is employed.
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* Otherwise,
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* tanh(x) = sinh(x)/cosh(x) = 1 - 2/(exp(2x) + 1).
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*
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*
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*
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* ACCURACY:
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*
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* Relative error:
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* arithmetic domain # trials peak rms
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* IEEE -2,2 30000 1.3e-19 2.4e-20
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*
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*/
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/*
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Cephes Math Library Release 2.7: May, 1998
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Copyright 1984, 1987, 1989, 1998 by Stephen L. Moshier
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*/
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/*
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Modified for mingw
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2002-07-22 Danny Smith <dannysmith@users.sourceforge.net>
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*/
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#ifdef __MINGW32__
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#include "cephes_mconf.h"
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#else
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#include "mconf.h"
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#endif
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#ifndef _SET_ERRNO
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#define _SET_ERRNO(x)
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#endif
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#ifdef UNK
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static long double P[] = {
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-6.8473739392677100872869E-5L,
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-9.5658283111794641589011E-1L,
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-8.4053568599672284488465E1L,
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-1.3080425704712825945553E3L,
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};
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static long double Q[] = {
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/* 1.0000000000000000000000E0L,*/
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9.6259501838840336946872E1L,
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1.8218117903645559060232E3L,
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3.9241277114138477845780E3L,
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};
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#endif
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#ifdef IBMPC
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static short P[] = {
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0xd2a4,0x1b0c,0x8f15,0x8f99,0xbff1, XPD
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0x5959,0x9111,0x9cc7,0xf4e2,0xbffe, XPD
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0xb576,0xef5e,0x6d57,0xa81b,0xc005, XPD
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0xe3be,0xbfbd,0x5cbc,0xa381,0xc009, XPD
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};
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static short Q[] = {
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/*0x0000,0x0000,0x0000,0x8000,0x3fff,*/
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0x687f,0xce24,0xdd6c,0xc084,0x4005, XPD
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0x3793,0xc95f,0xfa2f,0xe3b9,0x4009, XPD
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0xd5a2,0x1f9c,0x0b1b,0xf542,0x400a, XPD
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};
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#endif
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#ifdef MIEEE
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static long P[] = {
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0xbff10000,0x8f998f15,0x1b0cd2a4,
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0xbffe0000,0xf4e29cc7,0x91115959,
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0xc0050000,0xa81b6d57,0xef5eb576,
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0xc0090000,0xa3815cbc,0xbfbde3be,
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};
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static long Q[] = {
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/*0x3fff0000,0x80000000,0x00000000,*/
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0x40050000,0xc084dd6c,0xce24687f,
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0x40090000,0xe3b9fa2f,0xc95f3793,
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0x400a0000,0xf5420b1b,0x1f9cd5a2,
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};
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#endif
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#ifndef __MINGW32__
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extern long double MAXLOGL;
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#ifdef ANSIPROT
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extern long double fabsl ( long double );
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extern long double expl ( long double );
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extern long double polevll ( long double, void *, int );
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extern long double p1evll ( long double, void *, int );
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#else
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long double fabsl(), expl(), polevll(), p1evll();
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#endif
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#endif /* __MINGW32__ */
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long double tanhl(x)
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long double x;
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{
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long double s, z;
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#ifdef MINUSZERO
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if( x == 0.0L )
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return(x);
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#endif
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if (isnanl(x))
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{
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_SET_ERRNO (EDOM);
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return x;
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}
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z = fabsl(x);
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if( z > 0.5L * MAXLOGL )
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{
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_SET_ERRNO (ERANGE);
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if( x > 0 )
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return( 1.0L );
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else
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return( -1.0L );
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}
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if( z >= 0.625L )
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{
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s = expl(2.0*z);
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z = 1.0L - 2.0/(s + 1.0L);
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if( x < 0 )
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z = -z;
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}
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else
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{
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s = x * x;
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z = polevll( s, P, 3 )/p1evll(s, Q, 3);
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z = x * s * z;
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z = x + z;
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}
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return( z );
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}
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