80 lines
2.1 KiB
C
80 lines
2.1 KiB
C
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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) 2010-2011 Fredrik Johansson
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******************************************************************************/
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#include "fmpz_mat.h"
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void
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_fmpz_mat_inv_2x2(fmpz ** b, fmpz_t den, fmpz ** const a)
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{
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fmpz_t tmp;
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_fmpz_mat_det_cofactor_2x2(den, a);
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fmpz_neg(&b[0][1], &a[0][1]);
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fmpz_neg(&b[1][0], &a[1][0]);
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fmpz_init(tmp);
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fmpz_set(tmp, &a[0][0]);
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fmpz_set(&b[0][0], &a[1][1]);
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fmpz_set(&b[1][1], tmp);
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fmpz_clear(tmp);
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}
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int
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fmpz_mat_inv(fmpz_mat_t B, fmpz_t den, const fmpz_mat_t A)
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{
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slong dim = A->r;
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if (dim == 0)
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{
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fmpz_one(den);
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return 1;
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}
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else if (dim == 1)
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{
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fmpz_set(den, A->entries);
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fmpz_one(B->entries);
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return !fmpz_is_zero(den);
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}
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else if (dim == 2)
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{
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_fmpz_mat_inv_2x2(B->rows, den, A->rows);
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return !fmpz_is_zero(den);
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}
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else
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{
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fmpz_mat_t I;
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slong i;
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int success;
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fmpz_mat_init(I, dim, dim);
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for (i = 0; i < dim; i++)
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fmpz_one(fmpz_mat_entry(I, i, i));
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success = fmpz_mat_solve_fflu(B, den, A, I);
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fmpz_mat_clear(I);
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return success;
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}
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}
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