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/* -------------------------------------------------------------- */
/* (C)Copyright 2006,2007, */
/* International Business Machines Corporation */
/* All Rights Reserved. */
/* */
/* Redistribution and use in source and binary forms, with or */
/* without modification, are permitted provided that the */
/* following conditions are met: */
/* */
/* - Redistributions of source code must retain the above copyright*/
/* notice, this list of conditions and the following disclaimer. */
/* */
/* - Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials */
/* provided with the distribution. */
/* */
/* - Neither the name of IBM Corporation nor the names of its */
/* contributors may be used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* Redistributions of source code must retain the above copyright */
/* notice, this list of conditions and the following disclaimer. */
/* */
/* Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials */
/* provided with the distribution. */
/* */
/* Neither the name of IBM Corporation nor the names of its */
/* contributors may be used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND */
/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, */
/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */
/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE */
/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR */
/* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT */
/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */
/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) */
/* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN */
/* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR */
/* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, */
/* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
/* -------------------------------------------------------------- */
/* PROLOG END TAG zYx */
#ifdef __SPU__
#ifndef _TANHD2_H_
#define _TANHD2_H_ 1
#include <spu_intrinsics.h>
#include "expd2.h"
#include "divd2.h"
/*
* Taylor coefficients for tanh
*/
#define TANH_TAY01 1.000000000000000000000000000000E0
#define TANH_TAY02 -3.333333333333333333333333333333E-1
#define TANH_TAY03 1.333333333333333333333333333333E-1
#define TANH_TAY04 -5.396825396825396825396825396825E-2
#define TANH_TAY05 2.186948853615520282186948853616E-2
#define TANH_TAY06 -8.863235529902196568863235529902E-3
#define TANH_TAY07 3.592128036572481016925461369906E-3
#define TANH_TAY08 -1.455834387051318268249485180702E-3
#define TANH_TAY09 5.900274409455859813780759937000E-4
#define TANH_TAY10 -2.391291142435524814857314588851E-4
#define TANH_TAY11 9.691537956929450325595875000389E-5
#define TANH_TAY12 -3.927832388331683405337080809312E-5
#define TANH_TAY13 1.591890506932896474074427981657E-5
#define TANH_TAY14 -6.451689215655430763190842315303E-6
#define TANH_TAY15 2.614771151290754554263594256410E-6
#define TANH_TAY16 -1.059726832010465435091355394125E-6
#define TANH_TAY17 4.294911078273805854820351280397E-7
/*
* FUNCTION
* vector double _tanhd2(vector double x)
*
* DESCRIPTION
* The _tanhd2 function computes the hyperbolic tangent for each
* element of the input vector.
*
* We use the following to approximate tanh:
*
* |x| <= .25: Taylor Series
* |x| > .25: tanh(x) = (exp(2x) - 1)/(exp(2x) + 1)
*
*
* SPECIAL CASES:
* - tanh(+/- 0) = +/-0
* - tanh(+/- infinity) = +/- 1
* - tanh(NaN) = NaN
*
*/
static __inline vector double _tanhd2(vector double x)
{
vector double signbit = spu_splats(-0.0);
vector double oned = spu_splats(1.0);
vector double twod = spu_splats(2.0);
vector double infd = (vector double)spu_splats(0x7FF0000000000000ull);
vector double xabs;
vector double x2;
vector unsigned long long gttaylor;
vector double e;
vector double tresult;
vector double eresult;
vector double result;
xabs = spu_andc(x, signbit);
/*
* This is where we switch from Taylor Series
* to exponential formula.
*/
gttaylor = spu_cmpgt(xabs, spu_splats(0.25));
/*
* Taylor Series Approximation
*/
x2 = spu_mul(x,x);
tresult = spu_madd(x2, spu_splats(TANH_TAY11), spu_splats(TANH_TAY10));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY09));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY08));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY07));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY06));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY05));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY04));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY03));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY02));
tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY01));
tresult = spu_mul(xabs, tresult);
/*
* Exponential Formula
* Our expd2 function gives a more accurate result in general
* with xabs instead of x for x<0. We correct for sign later.
*/
e = _expd2(spu_mul(xabs, twod));
eresult = _divd2(spu_sub(e, oned), spu_add(e, oned));
/*
* Select Taylor or exp result.
*/
result = spu_sel(tresult, eresult, gttaylor);
/*
* Inf and NaN special cases. NaN is already in result
* for x = NaN.
*/
result = spu_sel(result, oned, spu_cmpeq(xabs, infd));
/*
* Antisymmetric function - preserve sign bit of x
* in the result.
*/
result = spu_sel(result, x, (vec_ullong2)signbit);
return result;
}
#endif /* _TANHD2_H_ */
#endif /* __SPU__ */
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