mirror of
https://github.com/vale981/arb
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41 lines
1.1 KiB
C
41 lines
1.1 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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void
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_arb_poly_newton_convergence_factor(arf_t convergence_factor,
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arb_srcptr poly, slong len,
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const arb_t convergence_interval, slong prec)
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{
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arb_ptr deriv;
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arb_t t, u;
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arb_init(t);
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arb_init(u);
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deriv = _arb_vec_init(len - 1);
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_arb_poly_derivative(deriv, poly, len, prec);
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_arb_poly_evaluate(t, deriv, len - 1, convergence_interval, prec);
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_arb_poly_derivative(deriv, deriv, len - 1, prec);
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_arb_poly_evaluate(u, deriv, len - 2, convergence_interval, prec);
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arb_div(t, u, t, prec);
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arb_mul_2exp_si(t, t, -1);
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arb_get_abs_ubound_arf(convergence_factor, t, prec);
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_arb_vec_clear(deriv, len - 1);
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arb_clear(t);
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arb_clear(u);
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}
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