/*
 *   surf - visualizing algebraic curves and algebraic surfaces
 *   Copyright (C) 1996-1997 Friedrich-Alexander-Universitaet
 *                           Erlangen-Nuernberg
 *                 1997-2000 Johannes Gutenberg-Universitaet Mainz
 *   Authors: Stephan Endrass, Hans Huelf, Ruediger Oertel,
 *            Kai Schneider, Ralf Schmitt, Johannes Beigel
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU 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 General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */


#include "resultant.h"

#include "Bezout.h"
#include "BigInteger.h"
#include "Timer.h"

// #define DEBUG
#include "debug.h"

static Bezout<BigInteger>::Coeff3Poly convertToBigIntPoly ( const Polyxyz &p)
{
	Bezout<BigInteger>::Coeff3Poly result;
	MonomXYZ mon;

	int i;
	for (i=0; i<p.GetNumber(); i++) {
		mon = p.Monom(i);
		BigInteger rat;
		rat = mon.Coeff()*1e15;
		if (!isNull(rat))
		    result.addMonom (monom(rat, mon.Exponent(0), mon.Exponent(1), mon.Exponent(2)));
	}
	return result;
}

static void addMonomFromBigInt (CMonom<BigInteger,2> *monom, void *ptr)
{
	Polyxy *poly = (Polyxy *) ptr;
	MonomXY monxy;
	monxy.SetCoeff (monom->getCoeff().asDouble());
	monxy.Exponent (0, monom->getExponent(0));
	monxy.Exponent (1, monom->getExponent(1));
	*poly += monxy;

}

Polyxy resultant (const Polyxyz &p1, const Polyxyz &p2)
{
	Thread::setDoing ("computing resultant");

	Bezout<BigInteger>::Coeff3Poly ip1 = convertToBigIntPoly (p1) ;
	Bezout<BigInteger>::Coeff3Poly ip2 = convertToBigIntPoly (p2) ;


	Bezout<BigInteger>::Coeff2Poly ires = Bezout<BigInteger>::resultant (ip1, ip2);

	Polyxy retval2;
	ires.withMonomsPerform (addMonomFromBigInt, &retval2);
	retval2.Norm();
	return retval2;
}