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68 lines
2.5 KiB
C
68 lines
2.5 KiB
C
/*
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* IBM Accurate Mathematical Library
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* written by International Business Machines Corp.
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* Copyright (C) 2001-2020 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses/>.
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*/
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/******************************************************************/
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/* MODULE_NAME: mpatan2.c */
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/* */
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/* FUNCTIONS:mpatan2 */
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/* */
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/* FILES NEEDED: mpa.h */
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/* mpa.c mpatan.c mpsqrt.c */
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/* */
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/* Multi-Precision Atan2(y,x) function subroutine, */
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/* for precision p >= 4. */
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/* y=0 is not permitted if x<=0. No error messages are given. */
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/* The relative error of the result is bounded by 44.84*r**(1-p) */
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/* if x <= 0, y != 0 and by 37.33*r**(1-p) if x>0. here r=2**24. */
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/* */
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/******************************************************************/
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#include "mpa.h"
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#ifndef SECTION
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# define SECTION
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#endif
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/* Multi-Precision Atan2 (y, x) function subroutine, for p >= 4.
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y = 0 is not permitted if x <= 0. No error messages are given. */
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void
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SECTION
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__mpatan2 (mp_no *y, mp_no *x, mp_no *z, int p)
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{
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mp_no mpt1, mpt2, mpt3;
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if (X[0] <= 0)
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{
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__dvd (x, y, &mpt1, p);
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__mul (&mpt1, &mpt1, &mpt2, p);
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if (mpt1.d[0] != 0)
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mpt1.d[0] = 1;
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__add (&mpt2, &__mpone, &mpt3, p);
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__mpsqrt (&mpt3, &mpt2, p);
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__add (&mpt1, &mpt2, &mpt3, p);
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mpt3.d[0] = Y[0];
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__mpatan (&mpt3, &mpt1, p);
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__add (&mpt1, &mpt1, z, p);
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}
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else
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{
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__dvd (y, x, &mpt1, p);
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__mpatan (&mpt1, z, p);
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}
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}
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