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66 lines
2.0 KiB
C
66 lines
2.0 KiB
C
/* k_cosf.c -- float version of k_cos.c
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Copyright (C) 2011-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Adhemerval Zanella <azanella@br.ibm.com>, 2011
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <http://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <fenv.h>
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#include <math_private.h>
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static const float twom27 = 7.4505806e-09;
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static const float dot3 = 3.0000001e-01;
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static const float dot78125 = 7.8125000e-01;
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static const float one = 1.0000000000e+00;
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static const float C1 = 4.1666667908e-02;
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static const float C2 = -1.3888889225e-03;
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static const float C3 = 2.4801587642e-05;
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static const float C4 = -2.7557314297e-07;
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static const float C5 = 2.0875723372e-09;
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static const float C6 = -1.1359647598e-11;
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float
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__kernel_cosf (float x, float y)
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{
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float a, hz, z, r, qx;
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float ix;
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ix = __builtin_fabsf (x);
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if (ix < twom27)
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{ /* |x| < 2**-27 */
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__feraiseexcept (FE_INEXACT);
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return one;
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}
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z = x * x;
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r = z * (C1 + z * (C2 + z * (C3 + z * (C4 + z * (C5 + z * C6)))));
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if (ix < dot3) /* if |x| < 0.3 */
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return one - ((float) 0.5 * z - (z * r - x * y));
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else
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{
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if (ix > dot78125)
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{ /* x > 0.78125 */
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qx = (float) 0.28125;
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}
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else
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{
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qx = ix / 4.0;
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}
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hz = (float) 0.5 *z - qx;
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a = one - qx;
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return a - (hz - (z * r - x * y));
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}
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}
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