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https://github.com/vale981/arb
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74 lines
2.1 KiB
C
74 lines
2.1 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) 2013 Fredrik Johansson
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******************************************************************************/
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#include "fmprb_calc.h"
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int fmprb_calc_newton_step(fmprb_t xnew, fmprb_calc_func_t func,
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void * param, const fmprb_t x, const fmprb_t conv_region,
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const fmpr_t conv_factor, long prec)
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{
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fmpr_t err;
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fmprb_t t;
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fmprb_struct u[2];
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int result;
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fmpr_init(err);
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fmprb_init(t);
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fmprb_init(u + 0);
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fmprb_init(u + 1);
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fmpr_mul(err, fmprb_radref(x), fmprb_radref(x), FMPRB_RAD_PREC, FMPR_RND_UP);
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fmpr_mul(err, err, conv_factor, FMPRB_RAD_PREC, FMPR_RND_UP);
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fmpr_set(fmprb_midref(t), fmprb_midref(x));
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fmpr_zero(fmprb_radref(t));
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func(u, t, param, 2, prec);
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fmprb_div(u, u, u + 1, prec);
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fmprb_sub(u, t, u, prec);
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fmprb_add_error_fmpr(u, err);
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if (fmprb_contains(conv_region, u) &&
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(fmpr_cmp(fmprb_radref(u), fmprb_radref(x)) < 0))
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{
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fmprb_swap(xnew, u);
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result = FMPRB_CALC_SUCCESS;
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}
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else
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{
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fmprb_set(xnew, x);
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result = FMPRB_CALC_NO_CONVERGENCE;
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}
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fmprb_clear(t);
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fmprb_clear(u);
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fmprb_clear(u + 1);
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fmpr_clear(err);
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return result;
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}
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