87 lines
2.1 KiB
C
87 lines
2.1 KiB
C
/*=============================================================================
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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) 2010 Fredrik Johansson
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******************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include "flint.h"
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#include "ulong_extras.h"
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#include "nmod_vec.h"
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#include "nmod_mat.h"
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#include "perm.h"
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mp_limb_t
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_nmod_mat_det(nmod_mat_t A)
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{
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mp_limb_t det;
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slong * P;
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slong m = A->r;
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slong rank;
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slong i;
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P = flint_malloc(sizeof(slong) * m);
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rank = nmod_mat_lu(P, A, 1);
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det = UWORD(0);
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if (rank == m)
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{
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det = UWORD(1);
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for (i = 0; i < m; i++)
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det = n_mulmod2_preinv(det, nmod_mat_entry(A, i, i),
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A->mod.n, A->mod.ninv);
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}
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if (_perm_parity(P, m) == 1)
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det = nmod_neg(det, A->mod);
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flint_free(P);
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return det;
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}
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mp_limb_t
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nmod_mat_det(const nmod_mat_t A)
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{
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nmod_mat_t tmp;
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mp_limb_t det;
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slong dim = A->r;
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if (dim != A->c)
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{
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flint_printf("Exception (nmod_mat_det). Non-square matrix.\n");
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abort();
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}
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if (dim == 0) return UWORD(1);
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if (dim == 1) return nmod_mat_entry(A, 0, 0);
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nmod_mat_init_set(tmp, A);
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det = _nmod_mat_det(tmp);
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nmod_mat_clear(tmp);
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return det;
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}
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