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/* poly/companion.c
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
static void set_companion_matrix (const double *a, size_t n, double *m);
static void
set_companion_matrix (const double *a, size_t nc, double *m)
{
size_t i, j;
for (i = 0; i < nc; i++)
for (j = 0; j < nc; j++)
MAT (m, i, j, nc) = 0.0;
for (i = 1; i < nc; i++)
MAT (m, i, i - 1, nc) = 1.0;
for (i = 0; i < nc; i++)
MAT (m, i, nc - 1, nc) = -a[i] / a[nc];
}
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