mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
103 lines
2.5 KiB
C
103 lines
2.5 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_evaluate2_rectangular(arb_t y, arb_t z, arb_srcptr poly,
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slong len, const arb_t x, slong prec)
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{
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slong i, j, m, r;
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arb_ptr xs;
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arb_t s, t, c;
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if (len < 3)
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{
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if (len == 0)
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{
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arb_zero(y);
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arb_zero(z);
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}
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else if (len == 1)
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{
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arb_set_round(y, poly + 0, prec);
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arb_zero(z);
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}
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else if (len == 2)
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{
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arb_mul(y, x, poly + 1, prec);
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arb_add(y, y, poly + 0, prec);
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arb_set_round(z, poly + 1, prec);
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}
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return;
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}
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m = n_sqrt(len) + 1;
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m *= 1;
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r = (len + m - 1) / m;
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xs = _arb_vec_init(m + 1);
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arb_init(s);
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arb_init(t);
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arb_init(c);
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_arb_vec_set_powers(xs, x, m + 1, prec);
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arb_set(y, poly + (r - 1) * m);
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for (j = 1; (r - 1) * m + j < len; j++)
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arb_addmul(y, xs + j, poly + (r - 1) * m + j, prec);
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for (i = r - 2; i >= 0; i--)
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{
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arb_set(s, poly + i * m);
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for (j = 1; j < m; j++)
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arb_addmul(s, xs + j, poly + i * m + j, prec);
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arb_mul(y, y, xs + m, prec);
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arb_add(y, y, s, prec);
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}
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len -= 1;
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r = (len + m - 1) / m;
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arb_mul_ui(z, poly + (r - 1) * m + 1, (r - 1) * m + 1, ARF_PREC_EXACT);
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for (j = 1; (r - 1) * m + j < len; j++)
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{
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arb_mul_ui(c, poly + (r - 1) * m + j + 1, (r - 1) * m + j + 1, ARF_PREC_EXACT);
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arb_addmul(z, xs + j, c, prec);
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}
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for (i = r - 2; i >= 0; i--)
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{
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arb_mul_ui(s, poly + i * m + 1, i * m + 1, ARF_PREC_EXACT);
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for (j = 1; j < m; j++)
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{
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arb_mul_ui(c, poly + i * m + j + 1, i * m + j + 1, ARF_PREC_EXACT);
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arb_addmul(s, xs + j, c, prec);
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}
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arb_mul(z, z, xs + m, prec);
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arb_add(z, z, s, prec);
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}
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_arb_vec_clear(xs, m + 1);
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arb_clear(s);
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arb_clear(t);
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arb_clear(c);
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}
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void
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arb_poly_evaluate2_rectangular(arb_t r, arb_t s, const arb_poly_t f, const arb_t a, slong prec)
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{
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_arb_poly_evaluate2_rectangular(r, s, f->coeffs, f->length, a, prec);
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}
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