109 lines
3.5 KiB
Plaintext
109 lines
3.5 KiB
Plaintext
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/*=============================================================================
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This file is part of FLINT.
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FLINT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FLINT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2011 Sebastian Pancratz
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Copyright (C) 2011 Fredrik Johansson
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******************************************************************************/
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*******************************************************************************
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Memory management
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*******************************************************************************
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slong * _perm_init(slong n)
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Initialises the permutation for use.
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void _perm_clear(slong *vec)
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Clears the permutation.
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*******************************************************************************
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Assignment
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*******************************************************************************
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void _perm_set(slong *res, const slong *vec, slong n)
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Sets the permutation \code{res} to the same as the permutation \code{vec}.
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void _perm_set_one(slong *vec, slong n)
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Sets the permutation to the identity permutation.
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void _perm_inv(slong *res, const slong *vec, slong n)
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Sets \code{res} to the inverse permutation of \code{vec}.
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Allows aliasing of \code{res} and \code{vec}.
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*******************************************************************************
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Composition
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*******************************************************************************
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void _perm_compose(slong *res, const slong *vec1, const slong *vec2, slong n)
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Forms the composition $\pi_1 \circ \pi_2$ of two permutations
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$\pi_1$ and $\pi_2$. Here, $\pi_2$ is applied first, that is,
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$(\pi_1 \circ \pi_2)(i) = \pi_1(\pi_2(i))$.
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Allows aliasing of \code{res}, \code{vec1} and \code{vec2}.
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*******************************************************************************
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Parity
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*******************************************************************************
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int _perm_parity(const slong *vec, slong n)
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Returns the parity of \code{vec}, 0 if the permutation is even and 1 if
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the permutation is odd.
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*******************************************************************************
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Randomisation
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*******************************************************************************
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int _perm_randtest(slong *vec, slong n, flint_rand_t state)
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Generates a random permutation vector of length $n$ and returns
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its parity, 0 or 1.
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This function uses the Knuth shuffle algorithm to generate a uniformly
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random permutation without retries.
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*******************************************************************************
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Input and output
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*******************************************************************************
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int _perm_print(const slong * vec, slong n)
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Prints the permutation vector of length $n$ to \code{stdout}.
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