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https://github.com/vale981/arb
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57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/*
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Copyright (C) 2012 Fredrik Johansson
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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 it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version. See <http://www.gnu.org/licenses/>.
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*/
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#include "acb_mat.h"
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int
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acb_cmpabs_approx(const acb_t x, const acb_t y)
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{
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const arf_struct *xm, *ym;
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if (arf_cmpabs(arb_midref(acb_realref(x)), arb_midref(acb_imagref(x))) >= 0)
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xm = arb_midref(acb_realref(x));
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else
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xm = arb_midref(acb_imagref(x));
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if (arf_cmpabs(arb_midref(acb_realref(y)), arb_midref(acb_imagref(y))) >= 0)
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ym = arb_midref(acb_realref(y));
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else
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ym = arb_midref(acb_imagref(y));
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return arf_cmpabs(xm, ym);
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}
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slong
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acb_mat_find_pivot_partial(const acb_mat_t mat,
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slong start_row, slong end_row, slong c)
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{
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slong 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 (!acb_contains_zero(acb_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 (acb_cmpabs_approx(acb_mat_entry(mat, i, c), acb_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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