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Diffstat (limited to 'gsl-1.9/permutation/permute_source.c')
| -rw-r--r-- | gsl-1.9/permutation/permute_source.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/gsl-1.9/permutation/permute_source.c b/gsl-1.9/permutation/permute_source.c new file mode 100644 index 0000000..6a35c4d --- /dev/null +++ b/gsl-1.9/permutation/permute_source.c @@ -0,0 +1,163 @@ +/* permutation/permute_source.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. + */ + +/* In-place Permutations + + permute: OUT[i] = IN[perm[i]] i = 0 .. N-1 + invpermute: OUT[perm[i]] = IN[i] i = 0 .. N-1 + + PERM is an index map, i.e. a vector which contains a permutation of + the integers 0 .. N-1. + + From Knuth "Sorting and Searching", Volume 3 (3rd ed), Section 5.2 + Exercise 10 (answers), p 617 + + FIXME: these have not been fully tested. +*/ + +int +TYPE (gsl_permute) (const size_t * p, ATOMIC * data, const size_t stride, const size_t n) +{ + size_t i, k, pk; + + for (i = 0; i < n; i++) + { + k = p[i]; + + while (k > i) + k = p[k]; + + if (k < i) + continue ; + + /* Now have k == i, i.e the least in its cycle */ + + pk = p[k]; + + if (pk == i) + continue ; + + /* shuffle the elements of the cycle */ + + { + unsigned int a; + + ATOMIC t[MULTIPLICITY]; + + for (a = 0; a < MULTIPLICITY; a++) + t[a] = data[i*stride*MULTIPLICITY + a]; + + while (pk != i) + { + for (a = 0; a < MULTIPLICITY; a++) + { + ATOMIC r1 = data[pk*stride*MULTIPLICITY + a]; + data[k*stride*MULTIPLICITY + a] = r1; + } + k = pk; + pk = p[k]; + }; + + for (a = 0; a < MULTIPLICITY; a++) + data[k*stride*MULTIPLICITY + a] = t[a]; + } + } + + return GSL_SUCCESS; +} + +int +FUNCTION (gsl_permute,inverse) (const size_t * p, ATOMIC * data, const size_t stride, const size_t n) +{ + size_t i, k, pk; + + for (i = 0; i < n; i++) + { + k = p[i]; + + while (k > i) + k = p[k]; + + if (k < i) + continue ; + + /* Now have k == i, i.e the least in its cycle */ + + pk = p[k]; + + if (pk == i) + continue ; + + /* shuffle the elements of the cycle in the inverse direction */ + + { + unsigned int a; + + ATOMIC t[MULTIPLICITY]; + + for (a = 0; a < MULTIPLICITY; a++) + t[a] = data[k*stride*MULTIPLICITY+a]; + + while (pk != i) + { + for (a = 0; a < MULTIPLICITY; a++) + { + ATOMIC r1 = data[pk*stride*MULTIPLICITY + a]; + data[pk*stride*MULTIPLICITY + a] = t[a]; + t[a] = r1; + } + + k = pk; + pk = p[k]; + }; + + for (a = 0; a < MULTIPLICITY; a++) + data[pk*stride*MULTIPLICITY+a] = t[a]; + } + } + + return GSL_SUCCESS; +} + + +int +TYPE (gsl_permute_vector) (const gsl_permutation * p, TYPE (gsl_vector) * v) +{ + if (v->size != p->size) + { + GSL_ERROR ("vector and permutation must be the same length", GSL_EBADLEN); + } + + TYPE (gsl_permute) (p->data, v->data, v->stride, v->size) ; + + return GSL_SUCCESS; +} + +int +FUNCTION (gsl_permute_vector,inverse) (const gsl_permutation * p, TYPE (gsl_vector) * v) +{ + if (v->size != p->size) + { + GSL_ERROR ("vector and permutation must be the same length", GSL_EBADLEN); + } + + FUNCTION (gsl_permute,inverse) (p->data, v->data, v->stride, v->size) ; + + return GSL_SUCCESS; +} |