111 lines
3.1 KiB
C
111 lines
3.1 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) 2011 Fredrik Johansson
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******************************************************************************/
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#include "fmpq_mat.h"
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int fmpq_mat_inv(fmpq_mat_t B, const fmpq_mat_t A)
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{
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slong n = A->r;
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if (n == 0)
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{
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return 1;
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}
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else if (n == 1)
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{
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if (fmpq_is_zero(fmpq_mat_entry(A, 0, 0)))
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return 0;
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fmpq_inv(fmpq_mat_entry(B, 0, 0), fmpq_mat_entry(A, 0, 0));
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return 1;
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}
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else if (n == 2)
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{
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fmpq_t d;
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int success;
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fmpq_init(d);
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fmpq_mul(d, fmpq_mat_entry(A, 0, 0), fmpq_mat_entry(A, 1, 1));
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fmpq_submul(d, fmpq_mat_entry(A, 0, 1), fmpq_mat_entry(A, 1, 0));
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success = !fmpq_is_zero(d);
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if (success)
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{
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fmpq_t t00, t01, t10, t11;
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fmpq_inv(d, d);
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fmpq_init(t00);
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fmpq_init(t01);
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fmpq_init(t10);
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fmpq_init(t11);
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fmpq_mul(t00, fmpq_mat_entry(A, 1, 1), d);
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fmpq_mul(t01, fmpq_mat_entry(A, 0, 1), d);
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fmpq_mul(t10, fmpq_mat_entry(A, 1, 0), d);
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fmpq_mul(t11, fmpq_mat_entry(A, 0, 0), d);
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fmpq_set(fmpq_mat_entry(B, 0, 0), t00);
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fmpq_neg(fmpq_mat_entry(B, 0, 1), t01);
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fmpq_neg(fmpq_mat_entry(B, 1, 0), t10);
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fmpq_set(fmpq_mat_entry(B, 1, 1), t11);
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fmpq_clear(t00);
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fmpq_clear(t01);
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fmpq_clear(t10);
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fmpq_clear(t11);
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}
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fmpq_clear(d);
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return success;
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}
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else
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{
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fmpz_mat_t Aclear, Bclear, I;
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fmpz * den;
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slong i;
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int success;
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fmpz_mat_init(Aclear, n, n);
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fmpz_mat_init(Bclear, n, n);
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fmpz_mat_init(I, n, n);
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den = _fmpz_vec_init(n);
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fmpq_mat_get_fmpz_mat_rowwise(Aclear, den, A);
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for (i = 0; i < n; i++)
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fmpz_set(fmpz_mat_entry(I, i, i), den + i);
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success = fmpz_mat_solve(Bclear, den, Aclear, I);
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if (success)
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fmpq_mat_set_fmpz_mat_div_fmpz(B, Bclear, den);
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fmpz_mat_clear(Aclear);
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fmpz_mat_clear(Bclear);
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fmpz_mat_clear(I);
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_fmpz_vec_clear(den, A->r);
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return success;
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}
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}
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