| /* 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]; |
| } |