mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
6bf072eb59
This will allow us to not loose the julia session on error. See also https://github.com/wbhart/flint2/pull/243
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/*
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Copyright (C) 2013 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 "arb_poly.h"
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static __inline__ slong _arf_mag(const arf_t c)
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{
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slong m = arf_abs_bound_lt_2exp_si(c);
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return FLINT_MAX(m, 0);
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}
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void
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_arb_poly_newton_refine_root(arb_t r, arb_srcptr poly, slong len,
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const arb_t start,
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const arb_t convergence_interval,
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const arf_t convergence_factor,
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slong eval_extra_prec,
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slong prec)
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{
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slong precs[FLINT_BITS];
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slong i, iters, wp, padding, start_prec;
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start_prec = arb_rel_accuracy_bits(start);
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padding = 5 + _arf_mag(convergence_factor);
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precs[0] = prec + padding;
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iters = 1;
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while ((iters < FLINT_BITS) && (precs[iters-1] + padding > 2*start_prec))
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{
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precs[iters] = (precs[iters-1] / 2) + padding;
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iters++;
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if (iters == FLINT_BITS)
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{
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flint_printf("newton_refine_root: initial value too imprecise\n");
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flint_abort();
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}
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}
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arb_set(r, start);
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for (i = iters - 1; i >= 0; i--)
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{
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wp = precs[i] + eval_extra_prec;
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if (!_arb_poly_newton_step(r, poly, len, r, convergence_interval,
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convergence_factor, wp))
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{
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flint_printf("warning: newton_refine_root: improvement failed\n");
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break;
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}
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}
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}
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