/*

 * IBM Accurate Mathematical Library

 * written by International Business Machines Corp.

 * Copyright (C) 2001-2018 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 <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

/* 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);

    }

}