mirror of
https://github.com/vale981/arb
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63 lines
1.7 KiB
C
63 lines
1.7 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_calc.h"
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int arb_calc_refine_root_newton(arb_t r, arb_calc_func_t func,
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void * param, const arb_t start, const arb_t conv_region,
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const arf_t conv_factor, slong eval_extra_prec, 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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int result;
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start_prec = arb_rel_accuracy_bits(start);
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if (arb_calc_verbose)
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flint_printf("newton initial accuracy: %wd\n", start_prec);
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padding = arf_abs_bound_lt_2exp_si(conv_factor);
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padding = FLINT_MIN(padding, prec) + 5;
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padding = FLINT_MAX(0, padding);
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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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return ARB_CALC_IMPRECISE_INPUT;
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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_calc_verbose)
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flint_printf("newton step: wp = %wd + %wd = %wd\n",
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precs[i], eval_extra_prec, wp);
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if ((result = arb_calc_newton_step(r, func, param,
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r, conv_region, conv_factor, wp)) != ARB_CALC_SUCCESS)
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{
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return result;
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}
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}
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return ARB_CALC_SUCCESS;
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}
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