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- /* 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 3 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 "gsl__config.h"
- #include "gsl_errno.h"
- #include "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;
- }
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