| /* combination/combination.c |
| * based on permutation/permutation.c by Brian Gough |
| * |
| * Copyright (C) 2001 Szymon Jaroszewicz |
| * |
| * 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. |
| */ |
| |
| #include <config.h> |
| #include <gsl/gsl_errno.h> |
| #include <gsl/gsl_combination.h> |
| |
| size_t |
| gsl_combination_n (const gsl_combination * c) |
| { |
| return c->n ; |
| } |
| |
| size_t |
| gsl_combination_k (const gsl_combination * c) |
| { |
| return c->k ; |
| } |
| |
| size_t * |
| gsl_combination_data (const gsl_combination * c) |
| { |
| return c->data ; |
| } |
| |
| #ifndef HIDE_INLINE_STATIC |
| size_t |
| gsl_combination_get (const gsl_combination * c, const size_t i) |
| { |
| if (gsl_check_range) |
| { |
| if (i >= c->k) /* size_t is unsigned, can't be negative */ |
| { |
| GSL_ERROR_VAL ("index out of range", GSL_EINVAL, 0); |
| } |
| } |
| |
| return c->data[i]; |
| } |
| #endif |
| |
| |
| int |
| gsl_combination_valid (gsl_combination * c) |
| { |
| const size_t n = c->n ; |
| const size_t k = c->k ; |
| |
| size_t i, j ; |
| |
| if( k > n ) |
| { |
| GSL_ERROR("combination has k greater than n", GSL_FAILURE) ; |
| } |
| for (i = 0; i < k; i++) |
| { |
| const size_t ci = c->data[i]; |
| |
| if (ci >= n) |
| { |
| GSL_ERROR("combination index outside range", GSL_FAILURE) ; |
| } |
| |
| for (j = 0; j < i; j++) |
| { |
| if (c->data[j] == ci) |
| { |
| GSL_ERROR("duplicate combination index", GSL_FAILURE) ; |
| } |
| if (c->data[j] > ci) |
| { |
| GSL_ERROR("combination indices not in increasing order", |
| GSL_FAILURE) ; |
| } |
| } |
| } |
| |
| return GSL_SUCCESS; |
| } |
| |
| |
| int |
| gsl_combination_next (gsl_combination * c) |
| { |
| /* Replaces c with the next combination (in the standard lexicographical |
| * ordering). Returns GSL_FAILURE if there is no next combination. |
| */ |
| const size_t n = c->n; |
| const size_t k = c->k; |
| size_t *data = c->data; |
| size_t i; |
| |
| if(k == 0) |
| { |
| return GSL_FAILURE; |
| } |
| i = k - 1; |
| |
| while(i > 0 && data[i] == n - k + i) |
| { |
| i--; |
| } |
| if(i == 0 && data[i] == n - k) |
| { |
| return GSL_FAILURE; |
| } |
| data[i]++; |
| for(; i < k - 1; i++) |
| { |
| data[i + 1] = data[i] + 1; |
| } |
| return GSL_SUCCESS; |
| } |
| |
| int |
| gsl_combination_prev (gsl_combination * c) |
| { |
| /* Replaces c with the previous combination (in the standard |
| * lexicographical ordering). Returns GSL_FAILURE if there is no |
| * previous combination. |
| */ |
| const size_t n = c->n; |
| const size_t k = c->k; |
| size_t *data = c->data; |
| size_t i; |
| |
| if(k == 0) |
| { |
| return GSL_FAILURE; |
| } |
| i = k - 1; |
| |
| while(i > 0 && data[i] == data[i-1] + 1) |
| { |
| i--; |
| } |
| if(i == 0 && data[i] == 0) |
| { |
| return GSL_FAILURE; |
| } |
| data[i++]--; |
| for(; i < k; i++) |
| { |
| data[i] = n - k + i; |
| } |
| return GSL_SUCCESS; |
| } |
| |
| int |
| gsl_combination_memcpy (gsl_combination * dest, const gsl_combination * src) |
| { |
| const size_t src_n = src->n; |
| const size_t src_k = src->k; |
| const size_t dest_n = dest->n; |
| const size_t dest_k = dest->k; |
| |
| if (src_n != dest_n || src_k != dest_k) |
| { |
| GSL_ERROR ("combination lengths are not equal", GSL_EBADLEN); |
| } |
| |
| { |
| size_t j; |
| |
| for (j = 0; j < src_k; j++) |
| { |
| dest->data[j] = src->data[j]; |
| } |
| } |
| |
| return GSL_SUCCESS; |
| } |