mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
114 lines
3.1 KiB
C
114 lines
3.1 KiB
C
/*=============================================================================
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This file is part of FLINT.
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FLINT 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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FLINT 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 FLINT; 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_mullow(fmpz * h, fmpz_t hexp, fmpz_t hrad,
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const fmpz * f, const fmpz_t fexp, const fmpz_t frad, long flen,
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const fmpz * g, const fmpz_t gexp, const fmpz_t grad, long glen,
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long maxbits, long trunc)
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{
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/* Multiply errors */
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if (fmpz_is_zero(frad) && fmpz_is_zero(grad))
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{
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fmpz_zero(hrad);
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}
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else
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{
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long terms;
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fmpz_t t;
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terms = FLINT_MIN(flen, glen);
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fmpz_init(t);
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/* For a single coefficient product, we have
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(a + r)(b + s) = a*b + s*a + r*b + r*s */
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fmpz_mul(t, frad, grad);
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_fmpz_addmul_abs(t, frad, g + _fmpz_vec_height_index(g, glen));
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_fmpz_addmul_abs(t, grad, f + _fmpz_vec_height_index(f, flen));
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/* add up for all terms */
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fmpz_mul_ui(hrad, t, terms);
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fmpz_clear(t);
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}
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/* Exact multiplication */
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if (flen >= glen)
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_fmpz_poly_mullow(h, f, flen, g, glen, trunc);
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else
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_fmpz_poly_mullow(h, g, glen, f, flen, trunc);
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fmpz_add(hexp, fexp, gexp);
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_arb_poly_normalise(h, hexp, hrad, trunc, maxbits);
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}
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void
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arb_poly_mullow(arb_poly_t z, const arb_poly_t x, const arb_poly_t y,
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long n)
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{
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long xlen, ylen;
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xlen = x->length;
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ylen = y->length;
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if (xlen == 0 || ylen == 0 || n == 0)
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{
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arb_poly_zero(z);
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return;
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}
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if (z == x)
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{
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arb_poly_t t;
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arb_poly_init(t, arb_poly_prec(x));
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arb_poly_set(t, x);
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arb_poly_mullow(z, t, y, n);
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arb_poly_clear(t);
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return;
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}
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if (z == y)
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{
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arb_poly_t t;
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arb_poly_init(t, arb_poly_prec(y));
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arb_poly_set(t, y);
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arb_poly_mullow(z, x, t, n);
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arb_poly_clear(t);
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return;
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}
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xlen = FLINT_MIN(xlen, n);
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ylen = FLINT_MIN(ylen, n);
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n = FLINT_MIN(n, xlen + ylen - 1);
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_arb_poly_fit_length(z, n);
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_arb_poly_mullow(z->coeffs, &z->exp, &z->rad,
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x->coeffs, &x->exp, &x->rad, xlen,
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y->coeffs, &y->exp, &y->rad, ylen,
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z->prec, n);
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z->length = n;
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}
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