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/*
* IBM Accurate Mathematical Library
* written by International Business Machines Corp.
* Copyright (C) 2001-2020 Free Software Foundation, Inc.
*
* 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 <https://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
/* 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)
{
mp_no mpt1, mpt2, mpt3;
if (X[0] <= 0)
{
__dvd (x, y, &mpt1, p);
__mul (&mpt1, &mpt1, &mpt2, p);
if (mpt1.d[0] != 0)
mpt1.d[0] = 1;
__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);
}
}
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