mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
96 lines
2.5 KiB
C
96 lines
2.5 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) 2012 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_interpolate_barycentric(arb_ptr poly,
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arb_srcptr xs, arb_srcptr ys, slong n, slong prec)
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{
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arb_ptr P, Q, w;
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arb_t t;
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slong i, j;
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if (n == 1)
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{
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arb_set(poly, ys);
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return;
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}
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P = _arb_vec_init(n + 1);
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Q = _arb_vec_init(n);
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w = _arb_vec_init(n);
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arb_init(t);
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_arb_poly_product_roots(P, xs, n, prec);
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for (i = 0; i < n; i++)
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{
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arb_one(w + i);
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for (j = 0; j < n; j++)
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{
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if (i != j)
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{
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arb_sub(t, xs + i, xs + j, prec);
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arb_mul(w + i, w + i, t, prec);
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}
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}
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arb_inv(w + i, w + i, prec);
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}
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_arb_vec_zero(poly, n);
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for (i = 0; i < n; i++)
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{
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_arb_poly_div_root(Q, t, P, n + 1, xs + i, prec);
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arb_mul(t, w + i, ys + i, prec);
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_arb_vec_scalar_addmul(poly, Q, n, t, prec);
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}
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_arb_vec_clear(P, n + 1);
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_arb_vec_clear(Q, n);
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_arb_vec_clear(w, n);
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arb_clear(t);
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}
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void
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arb_poly_interpolate_barycentric(arb_poly_t poly,
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arb_srcptr xs, arb_srcptr ys, slong n, slong prec)
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{
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if (n == 0)
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{
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arb_poly_zero(poly);
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}
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else
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{
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arb_poly_fit_length(poly, n);
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_arb_poly_set_length(poly, n);
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_arb_poly_interpolate_barycentric(poly->coeffs,
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xs, ys, n, prec);
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_arb_poly_normalise(poly);
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}
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}
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