mirror of
https://github.com/vale981/arb
synced 2025-03-04 17:01:40 -05:00
120 lines
2.8 KiB
C
120 lines
2.8 KiB
C
/*
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Copyright (C) 2012 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 "acb_poly.h"
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void
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_acb_poly_mullow_transpose(acb_ptr res,
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acb_srcptr poly1, slong len1,
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acb_srcptr poly2, slong len2, slong n, slong prec)
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{
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arb_ptr a, b, c, d, e, f, w;
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arb_ptr t;
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slong i;
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len1 = FLINT_MIN(len1, n);
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len2 = FLINT_MIN(len2, n);
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w = flint_malloc(sizeof(arb_struct) * (2 * (len1 + len2 + n)));
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a = w;
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b = a + len1;
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c = b + len1;
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d = c + len2;
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e = d + len2;
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f = e + n;
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/* (e+fi) = (a+bi)(c+di) = (ac - bd) + (ad + bc)i */
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t = _arb_vec_init(n);
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for (i = 0; i < len1; i++)
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{
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a[i] = *acb_realref(poly1 + i);
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b[i] = *acb_imagref(poly1 + i);
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}
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for (i = 0; i < len2; i++)
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{
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c[i] = *acb_realref(poly2 + i);
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d[i] = *acb_imagref(poly2 + i);
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}
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for (i = 0; i < n; i++)
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{
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e[i] = *acb_realref(res + i);
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f[i] = *acb_imagref(res + i);
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}
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_arb_poly_mullow(e, a, len1, c, len2, n, prec);
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_arb_poly_mullow(t, b, len1, d, len2, n, prec);
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_arb_vec_sub(e, e, t, n, prec);
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_arb_poly_mullow(f, a, len1, d, len2, n, prec);
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/* squaring */
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if (poly1 == poly2 && len1 == len2)
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{
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_arb_vec_scalar_mul_2exp_si(f, f, n, 1);
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}
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else
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{
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_arb_poly_mullow(t, b, len1, c, len2, n, prec);
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_arb_vec_add(f, f, t, n, prec);
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}
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for (i = 0; i < n; i++)
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{
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*acb_realref(res + i) = e[i];
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*acb_imagref(res + i) = f[i];
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}
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_arb_vec_clear(t, n);
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flint_free(w);
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}
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void
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acb_poly_mullow_transpose(acb_poly_t res, const acb_poly_t poly1,
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const acb_poly_t poly2,
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slong n, slong prec)
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{
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slong len1, len2;
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len1 = poly1->length;
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len2 = poly2->length;
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if (len1 == 0 || len2 == 0 || n == 0)
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{
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acb_poly_zero(res);
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return;
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}
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n = FLINT_MIN((len1 + len2 - 1), n);
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len1 = FLINT_MIN(len1, n);
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len2 = FLINT_MIN(len2, n);
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if (res == poly1 || res == poly2)
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{
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acb_poly_t t;
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acb_poly_init2(t, n);
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_acb_poly_mullow_transpose(t->coeffs, poly1->coeffs, len1,
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poly2->coeffs, len2, n, prec);
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acb_poly_swap(res, t);
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acb_poly_clear(t);
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}
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else
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{
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acb_poly_fit_length(res, n);
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_acb_poly_mullow_transpose(res->coeffs, poly1->coeffs, len1,
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poly2->coeffs, len2, n, prec);
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}
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_acb_poly_set_length(res, n);
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_acb_poly_normalise(res);
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}
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