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75 lines
2.8 KiB
C
75 lines
2.8 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, 2011 Free Software Foundation
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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 <http://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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void __mpsqrt(mp_no *, mp_no *, int);
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void __mpatan(mp_no *, mp_no *, int);
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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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static const double ZERO = 0.0, ONE = 1.0;
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mp_no mpone = {0,{0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,
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0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,
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0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0}};
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mp_no mpt1,mpt2,mpt3;
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if (X[0] <= ZERO) {
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mpone.e = 1; mpone.d[0] = mpone.d[1] = ONE;
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__dvd(x,y,&mpt1,p); __mul(&mpt1,&mpt1,&mpt2,p);
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if (mpt1.d[0] != ZERO) mpt1.d[0] = ONE;
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__add(&mpt2,&mpone,&mpt3,p); __mpsqrt(&mpt3,&mpt2,p);
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__add(&mpt1,&mpt2,&mpt3,p); mpt3.d[0]=Y[0];
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__mpatan(&mpt3,&mpt1,p); __add(&mpt1,&mpt1,z,p);
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}
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else
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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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return;
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}
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