mirror of
https://github.com/vale981/arb
synced 2025-03-06 09:51:39 -05:00
136 lines
3.3 KiB
C
136 lines
3.3 KiB
C
/*=============================================================================
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This file is part of ARB.
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ARB 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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ARB 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 ARB; 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) 2012 Fredrik Johansson
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******************************************************************************/
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#include "fmprb_mat.h"
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static __inline__ void
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fmprb_mat_swap_rows(fmprb_mat_t mat, long * perm, long r, long s)
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{
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if (r != s)
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{
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fmprb_struct * u;
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long t;
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if (perm != NULL)
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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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static __inline__ long
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fmprb_mat_find_pivot_partial(const fmprb_mat_t mat,
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long start_row, long end_row, long c)
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{
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long best_row, i;
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best_row = -1;
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for (i = start_row; i < end_row; i++)
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{
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if (!fmprb_contains_zero(fmprb_mat_entry(mat, i, c)))
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{
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if (best_row == -1)
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{
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best_row = i;
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}
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/* todo: should take the radius into account */
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else if (fmpr_cmpabs(fmprb_midref(fmprb_mat_entry(mat, i, c)),
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fmprb_midref(fmprb_mat_entry(mat, best_row, c))) > 0)
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{
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best_row = i;
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}
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}
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}
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return best_row;
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}
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int
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fmprb_mat_lu(long * P, fmprb_mat_t LU, const fmprb_mat_t A, long prec)
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{
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fmprb_t d, e;
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fmprb_struct ** a;
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long i, j, m, n, r, length, row, col;
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int result;
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m = fmprb_mat_nrows(A);
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n = fmprb_mat_ncols(A);
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result = 1;
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if (m == 0 || n == 0)
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return result;
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fmprb_mat_set(LU, A);
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a = LU->rows;
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row = col = 0;
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for (i = 0; i < m; i++)
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P[i] = i;
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fmprb_init(d);
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fmprb_init(e);
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while (row < m && col < n)
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{
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r = fmprb_mat_find_pivot_partial(LU, row, m, col);
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if (r == -1)
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{
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result = 0;
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break;
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}
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else if (r != row)
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fmprb_mat_swap_rows(LU, P, row, r);
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fmprb_set(d, a[row] + col);
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for (j = row + 1; j < m; j++)
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{
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fmprb_div(e, a[j] + col, d, prec);
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fmprb_neg(e, e);
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_fmprb_vec_scalar_addmul(a[j] + col,
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a[row] + col, n - col, e, prec);
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fmprb_zero(a[j] + col);
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fmprb_neg(a[j] + row, e);
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}
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row++;
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col++;
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}
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fmprb_clear(d);
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fmprb_clear(e);
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return result;
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}
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