87 lines
2.5 KiB
C
87 lines
2.5 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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slong
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fmpq_mat_rref_classical(fmpq_mat_t B, const fmpq_mat_t A)
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{
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slong m, n, i, j, pivot_row, pivot_col, rank;
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m = A->r;
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n = A->c;
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if (m == 0 || n == 0)
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return 0;
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if (A != B)
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fmpq_mat_set(B, A);
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rank = 0;
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pivot_row = 0;
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pivot_col = 0;
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while (pivot_row < m && pivot_col < n)
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{
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if (!fmpq_mat_pivot(NULL, B, pivot_row, pivot_col))
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{
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pivot_col++;
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continue;
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}
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rank++;
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/* Scale row to have 1 as leading entry */
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for (j = pivot_col + 1; j < n; j++)
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{
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fmpq_div(fmpq_mat_entry(B, pivot_row, j),
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fmpq_mat_entry(B, pivot_row, j),
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fmpq_mat_entry(B, pivot_row, pivot_col));
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}
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/* Eliminate rows above and below */
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for (i = 0; i < m; i++)
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{
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if (i == pivot_row ||
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fmpq_is_zero(fmpq_mat_entry(B, i, pivot_col)))
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continue;
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for (j = pivot_col + 1; j < n; j++)
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fmpq_submul(fmpq_mat_entry(B, i, j),
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fmpq_mat_entry(B, pivot_row, j),
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fmpq_mat_entry(B, i, pivot_col));
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}
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/* Clear pivot column */
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for (i = 0; i < m; i++)
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fmpq_set_si(fmpq_mat_entry(B, i, pivot_col), i == pivot_row, 1);
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pivot_row++;
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pivot_col++;
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}
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return rank;
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}
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