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/*
* IBM Accurate Mathematical Library
* written by International Business Machines Corp.
* Copyright (C) 2001, 2011 Free Software Foundation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
/******************************************************************/
/* MODULE_NAME: mpatan2.c */
/* */
/* FUNCTIONS:mpatan2 */
/* */
/* FILES NEEDED: mpa.h */
/* mpa.c mpatan.c mpsqrt.c */
/* */
/* Multi-Precision Atan2(y,x) function subroutine, */
/* for precision p >= 4. */
/* y=0 is not permitted if x<=0. No error messages are given. */
/* The relative error of the result is bounded by 44.84*r**(1-p) */
/* if x <= 0, y != 0 and by 37.33*r**(1-p) if x>0. here r=2**24. */
/* */
/******************************************************************/
#include "mpa.h"
#ifndef SECTION
# define SECTION
#endif
void __mpsqrt(mp_no *, mp_no *, int);
void __mpatan(mp_no *, mp_no *, int);
/* Multi-Precision Atan2(y,x) function subroutine, for p >= 4. */
/* y=0 is not permitted if x<=0. No error messages are given. */
void
SECTION
__mpatan2(mp_no *y, mp_no *x, mp_no *z, int p) {
static const double ZERO = 0.0, ONE = 1.0;
mp_no mpt1,mpt2,mpt3;
if (X[0] <= ZERO) {
__dvd(x,y,&mpt1,p); __mul(&mpt1,&mpt1,&mpt2,p);
if (mpt1.d[0] != ZERO) mpt1.d[0] = ONE;
__add(&mpt2,&mpone,&mpt3,p); __mpsqrt(&mpt3,&mpt2,p);
__add(&mpt1,&mpt2,&mpt3,p); mpt3.d[0]=Y[0];
__mpatan(&mpt3,&mpt1,p); __add(&mpt1,&mpt1,z,p);
}
else
{ __dvd(y,x,&mpt1,p);
__mpatan(&mpt1,z,p);
}
return;
}
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