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/*
* IBM Accurate Mathematical Library
* Copyright (c) International Business Machines Corp., 2001
*
* 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 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 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/******************************************************************/
/* 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"
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 mpatan2(mp_no *y, mp_no *x, mp_no *z, int p) {
static const double ZERO = 0.0, ONE = 1.0;
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,
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,
0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,};
mp_no mpt1,mpt2,mpt3;
if (X[0] <= ZERO) {
mpone.e = 1; mpone.d[0] = mpone.d[1] = ONE;
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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