linbox
examples/bigmat.C

Outputs a big and very sparse matrix.let C be the cyclic shift matrix with 1 on the 1,n position and along the first subdiagonal.

This matrix is $2C + 3I$. It has 2 nonzero entries per row and per column. It is an $ n \times n$ matrix whose determinant is considerably less than the Hadamard bound (but is large – 3^n +- 2^n).

/*
* examples/bigmat.C
*
* Copyright (C) 2007, 2010 B Youse, D. Saunders
* ========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 <iostream>
#include <cstdlib>
using namespace std;
int main(int argc, char* argv[])
{
if (argc != 2 ) {
cerr << "Usage: bigmat <n>, where <n> is the size you like." << endl;
return -1;
}
int n = atoi(argv[1]);
cout << n << " " << n << " M" << endl;
cout << "1 1 3" << endl;
cout << "1 " << n << " 2" << endl;
for (int i = 2; i <=n; ++i)
{
cout << i << " " << i-1 << " " << 2 << endl;
cout << i << " " << i << " " << 3 << endl;
}
cout << "0 0 0" << endl;
return 0 ;
}
// vim:sts=8:sw=8:ts=8:noet:sr:cino=>s,f0,{0,g0,(0,:0,t0,+0,=s
// Local Variables:
// mode: C++
// tab-width: 8
// indent-tabs-mode: nil
// c-basic-offset: 8
// End: