diff options
Diffstat (limited to 'gsl-1.9/eigen/sort.c')
| -rw-r--r-- | gsl-1.9/eigen/sort.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/gsl-1.9/eigen/sort.c b/gsl-1.9/eigen/sort.c new file mode 100644 index 0000000..d0755d9 --- /dev/null +++ b/gsl-1.9/eigen/sort.c @@ -0,0 +1,235 @@ +/* eigen/eigen_sort.c + * + * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman + * + * 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. + */ + +/* Author: G. Jungman, Modified: B. Gough. */ + +#include <config.h> +#include <stdlib.h> +#include <gsl/gsl_math.h> +#include <gsl/gsl_eigen.h> +#include <gsl/gsl_complex.h> +#include <gsl/gsl_complex_math.h> + +/* The eigen_sort below is not very good, but it is simple and + * self-contained. We can always implement an improved sort later. */ + +int +gsl_eigen_symmv_sort (gsl_vector * eval, gsl_matrix * evec, + gsl_eigen_sort_t sort_type) +{ + if (evec->size1 != evec->size2) + { + GSL_ERROR ("eigenvector matrix must be square", GSL_ENOTSQR); + } + else if (eval->size != evec->size1) + { + GSL_ERROR ("eigenvalues must match eigenvector matrix", GSL_EBADLEN); + } + else + { + const size_t N = eval->size; + size_t i; + + for (i = 0; i < N - 1; i++) + { + size_t j; + size_t k = i; + + double ek = gsl_vector_get (eval, i); + + /* search for something to swap */ + for (j = i + 1; j < N; j++) + { + int test; + const double ej = gsl_vector_get (eval, j); + + switch (sort_type) + { + case GSL_EIGEN_SORT_VAL_ASC: + test = (ej < ek); + break; + case GSL_EIGEN_SORT_VAL_DESC: + test = (ej > ek); + break; + case GSL_EIGEN_SORT_ABS_ASC: + test = (fabs (ej) < fabs (ek)); + break; + case GSL_EIGEN_SORT_ABS_DESC: + test = (fabs (ej) > fabs (ek)); + break; + default: + GSL_ERROR ("unrecognized sort type", GSL_EINVAL); + } + + if (test) + { + k = j; + ek = ej; + } + } + + if (k != i) + { + /* swap eigenvalues */ + gsl_vector_swap_elements (eval, i, k); + + /* swap eigenvectors */ + gsl_matrix_swap_columns (evec, i, k); + } + } + + return GSL_SUCCESS; + } +} + + +int +gsl_eigen_hermv_sort (gsl_vector * eval, gsl_matrix_complex * evec, + gsl_eigen_sort_t sort_type) +{ + if (evec->size1 != evec->size2) + { + GSL_ERROR ("eigenvector matrix must be square", GSL_ENOTSQR); + } + else if (eval->size != evec->size1) + { + GSL_ERROR ("eigenvalues must match eigenvector matrix", GSL_EBADLEN); + } + else + { + const size_t N = eval->size; + size_t i; + + for (i = 0; i < N - 1; i++) + { + size_t j; + size_t k = i; + + double ek = gsl_vector_get (eval, i); + + /* search for something to swap */ + for (j = i + 1; j < N; j++) + { + int test; + const double ej = gsl_vector_get (eval, j); + + switch (sort_type) + { + case GSL_EIGEN_SORT_VAL_ASC: + test = (ej < ek); + break; + case GSL_EIGEN_SORT_VAL_DESC: + test = (ej > ek); + break; + case GSL_EIGEN_SORT_ABS_ASC: + test = (fabs (ej) < fabs (ek)); + break; + case GSL_EIGEN_SORT_ABS_DESC: + test = (fabs (ej) > fabs (ek)); + break; + default: + GSL_ERROR ("unrecognized sort type", GSL_EINVAL); + } + + if (test) + { + k = j; + ek = ej; + } + } + + if (k != i) + { + /* swap eigenvalues */ + gsl_vector_swap_elements (eval, i, k); + + /* swap eigenvectors */ + gsl_matrix_complex_swap_columns (evec, i, k); + } + } + + return GSL_SUCCESS; + } +} + +int +gsl_eigen_nonsymmv_sort (gsl_vector_complex * eval, + gsl_matrix_complex * evec, + gsl_eigen_sort_t sort_type) +{ + if (evec->size1 != evec->size2) + { + GSL_ERROR ("eigenvector matrix must be square", GSL_ENOTSQR); + } + else if (eval->size != evec->size1) + { + GSL_ERROR ("eigenvalues must match eigenvector matrix", GSL_EBADLEN); + } + else + { + const size_t N = eval->size; + size_t i; + + for (i = 0; i < N - 1; i++) + { + size_t j; + size_t k = i; + + gsl_complex ek = gsl_vector_complex_get (eval, i); + + /* search for something to swap */ + for (j = i + 1; j < N; j++) + { + int test; + const gsl_complex ej = gsl_vector_complex_get (eval, j); + + switch (sort_type) + { + case GSL_EIGEN_SORT_ABS_ASC: + test = (gsl_complex_abs (ej) < gsl_complex_abs (ek)); + break; + case GSL_EIGEN_SORT_ABS_DESC: + test = (gsl_complex_abs (ej) > gsl_complex_abs (ek)); + break; + case GSL_EIGEN_SORT_VAL_ASC: + case GSL_EIGEN_SORT_VAL_DESC: + default: + GSL_ERROR ("invalid sort type", GSL_EINVAL); + } + + if (test) + { + k = j; + ek = ej; + } + } + + if (k != i) + { + /* swap eigenvalues */ + gsl_vector_complex_swap_elements (eval, i, k); + + /* swap eigenvectors */ + gsl_matrix_complex_swap_columns (evec, i, k); + } + } + + return GSL_SUCCESS; + } +} |