mirror of
https://github.com/vale981/arb
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55 lines
1.8 KiB
C
55 lines
1.8 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 "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, long len,
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const arb_t convergence_interval, long 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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