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Diffstat (limited to 'gsl-1.9/poly/balance.c')
-rw-r--r-- | gsl-1.9/poly/balance.c | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/gsl-1.9/poly/balance.c b/gsl-1.9/poly/balance.c new file mode 100644 index 0000000..a1f7916 --- /dev/null +++ b/gsl-1.9/poly/balance.c @@ -0,0 +1,127 @@ +/* poly/balance.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 balance_companion_matrix (double *m, size_t n); + +#define RADIX 2 +#define RADIX2 (RADIX*RADIX) + +static void +balance_companion_matrix (double *m, size_t nc) +{ + int not_converged = 1; + + double row_norm = 0; + double col_norm = 0; + + while (not_converged) + { + size_t i, j; + double g, f, s; + + not_converged = 0; + + for (i = 0; i < nc; i++) + { + /* column norm, excluding the diagonal */ + + if (i != nc - 1) + { + col_norm = fabs (MAT (m, i + 1, i, nc)); + } + else + { + col_norm = 0; + + for (j = 0; j < nc - 1; j++) + { + col_norm += fabs (MAT (m, j, nc - 1, nc)); + } + } + + /* row norm, excluding the diagonal */ + + if (i == 0) + { + row_norm = fabs (MAT (m, 0, nc - 1, nc)); + } + else if (i == nc - 1) + { + row_norm = fabs (MAT (m, i, i - 1, nc)); + } + else + { + row_norm = (fabs (MAT (m, i, i - 1, nc)) + + fabs (MAT (m, i, nc - 1, nc))); + } + + if (col_norm == 0 || row_norm == 0) + { + continue; + } + + g = row_norm / RADIX; + f = 1; + s = col_norm + row_norm; + + while (col_norm < g) + { + f *= RADIX; + col_norm *= RADIX2; + } + + g = row_norm * RADIX; + + while (col_norm > g) + { + f /= RADIX; + col_norm /= RADIX2; + } + + if ((row_norm + col_norm) < 0.95 * s * f) + { + not_converged = 1; + + g = 1 / f; + + if (i == 0) + { + MAT (m, 0, nc - 1, nc) *= g; + } + else + { + MAT (m, i, i - 1, nc) *= g; + MAT (m, i, nc - 1, nc) *= g; + } + + if (i == nc - 1) + { + for (j = 0; j < nc; j++) + { + MAT (m, j, i, nc) *= f; + } + } + else + { + MAT (m, i + 1, i, nc) *= f; + } + } + } + } +} |