113 lines
3.0 KiB
C
113 lines
3.0 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) 2011 Fredrik Johansson
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******************************************************************************/
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#include "flint.h"
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#include "nmod_poly.h"
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#include "nmod_poly_mat.h"
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#define E(j,k) nmod_poly_mat_entry(B,j,k)
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static __inline__ void
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nmod_poly_mat_swap_rows(nmod_poly_mat_t mat, slong * perm, slong r, slong s)
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{
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if (r != s)
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{
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nmod_poly_struct * u;
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slong t;
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if (perm)
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{
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t = perm[s];
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perm[s] = perm[r];
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perm[r] = t;
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}
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u = mat->rows[s];
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mat->rows[s] = mat->rows[r];
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mat->rows[r] = u;
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}
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}
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slong
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nmod_poly_mat_fflu(nmod_poly_mat_t B, nmod_poly_t den, slong * perm,
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const nmod_poly_mat_t A, int rank_check)
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{
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nmod_poly_t t;
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slong m, n, j, k, rank, r, pivot_row, pivot_col;
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if (nmod_poly_mat_is_empty(A))
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{
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nmod_poly_one(den);
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return 0;
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}
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nmod_poly_mat_set(B, A);
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m = B->r;
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n = B->c;
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rank = pivot_row = pivot_col = 0;
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nmod_poly_init(t, nmod_poly_mat_modulus(A));
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while (pivot_row < m && pivot_col < n)
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{
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r = nmod_poly_mat_find_pivot_partial(B, pivot_row, m, pivot_col);
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if (r == -1)
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{
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if (rank_check)
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{
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nmod_poly_zero(den);
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rank = 0;
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break;
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}
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pivot_col++;
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continue;
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}
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else if (r != pivot_row)
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nmod_poly_mat_swap_rows(B, perm, pivot_row, r);
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rank++;
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for (j = pivot_row + 1; j < m; j++)
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{
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for (k = pivot_col + 1; k < n; k++)
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{
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nmod_poly_mul(E(j, k), E(j, k), E(pivot_row, pivot_col));
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nmod_poly_mul(t, E(j, pivot_col), E(pivot_row, k));
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nmod_poly_sub(E(j, k), E(j, k), t);
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if (pivot_row > 0)
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nmod_poly_div(E(j, k), E(j, k), den);
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}
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}
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nmod_poly_set(den, E(pivot_row, pivot_col));
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pivot_row++;
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pivot_col++;
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}
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nmod_poly_clear(t);
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return rank;
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}
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