examples/det.C

Determinant of sparse matrix over Z or Zp.

/*
 * examples/det.C
 *
 * Copyright (C) 2005, 2010 D. Saunders,  J-G. Dumas
 * ========LICENCE========
 * This file is part of the library LinBox.
 *
 * LinBox 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 library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * ========LICENCE========
 */

#include <linbox/linbox-config.h>
#include <iostream>

#include <linbox/ring/modular.h>
#include <linbox/matrix/sparse-matrix.h>
#include <linbox/solutions/det.h>

using namespace LinBox;
using namespace std;

int main (int argc, char **argv)
{
    commentator().setMaxDetailLevel (-1);
    commentator().setMaxDepth (-1);
    commentator().setReportStream (std::cerr);

    if (argc <= 1 || argc > 3) {
        cerr << "Usage: det <matrix-file-in-supported-format> [<p>]" << endl;
        return -1;
    }

    if (argc == 2 ) {

        // For a small integer matrix test, do "det data/mat2S".
        // It is a 2 by 2 matrix with determinant = -2.

        typedef Givaro::ZRing<Integer> Integers;
        Integers ZZ;

        ifstream input (argv[1]);
        if (!input)
        { cerr << "Error opening matrix file " << argv[1] << endl;
            return -1;
        }
        DenseMatrix<Integers> A(ZZ); A.read(input);
        cout << "Matrix is " << A.rowdim() << " by " << A.coldim() << endl;

        Integers::Element det_A;
        det (det_A, A);

        cout << "Determinant is ";
        ZZ.write(cout, det_A) << endl;
    }
    if (argc == 3) {

        typedef Givaro::Modular<double> Field;
        double q = atof(argv[2]);
        Field F(q);

        ifstream input (argv[1]);
        if (!input)
        { cerr << "Error opening matrix file " << argv[1] << endl;
            return -1;
        }
        SparseMatrix<Field> B (F); B.read(input);
        cout << "Matrix is " << B.rowdim() << " by " << B.coldim() << endl;

        Field::Element det_B;
        det (det_B, B);

        cout << "Determinant is ";
        F.write(cout, det_B) << " mod " << q << endl;
    }

    return 0;
}

// Local Variables:
// mode: C++
// tab-width: 4
// indent-tabs-mode: nil
// c-basic-offset: 4
// End:
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