62 lines
1.9 KiB
C
62 lines
1.9 KiB
C
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/* From: @(#)k_cos.c 1.3 95/01/18 */
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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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* Copyright (c) 2008 Steven G. Kargl, David Schultz, Bruce D. Evans.
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*
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* Developed at SunSoft, 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 <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/*
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* ld128 version of k_cos.c. See ../src/k_cos.c for most comments.
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*/
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#include "math_private.h"
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/*
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* Domain [-0.7854, 0.7854], range ~[-1.80e-37, 1.79e-37]:
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* |cos(x) - c(x))| < 2**-122.0
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*
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* 113-bit precision requires more care than 64-bit precision, since
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* simple methods give a minimax polynomial with coefficient for x^2
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* that is 1 ulp below 0.5, but we want it to be precisely 0.5. See
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* ../ld80/k_cosl.c for more details.
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*/
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static const double
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one = 1.0;
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static const long double
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C1 = 0.04166666666666666666666666666666658424671L,
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C2 = -0.001388888888888888888888888888863490893732L,
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C3 = 0.00002480158730158730158730158600795304914210L,
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C4 = -0.2755731922398589065255474947078934284324e-6L,
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C5 = 0.2087675698786809897659225313136400793948e-8L,
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C6 = -0.1147074559772972315817149986812031204775e-10L,
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C7 = 0.4779477332386808976875457937252120293400e-13L;
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static const double
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C8 = -0.1561920696721507929516718307820958119868e-15,
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C9 = 0.4110317413744594971475941557607804508039e-18,
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C10 = -0.8896592467191938803288521958313920156409e-21,
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C11 = 0.1601061435794535138244346256065192782581e-23;
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long double
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__kernel_cosl(long double x, long double y)
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{
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long double hz,z,r,w;
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z = x*x;
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r = z*(C1+z*(C2+z*(C3+z*(C4+z*(C5+z*(C6+z*(C7+
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z*(C8+z*(C9+z*(C10+z*C11))))))))));
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hz = 0.5*z;
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w = one-hz;
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return w + (((one-w)-hz) + (z*r-x*y));
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}
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