arb/acb_poly/mullow_transpose_gauss.c
2016-04-26 17:20:05 +02:00

119 lines
2.8 KiB
C

/*
Copyright (C) 2012 Fredrik Johansson
This file is part of Arb.
Arb is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "acb_poly.h"
void
_acb_poly_mullow_transpose_gauss(acb_ptr res,
acb_srcptr poly1, slong len1,
acb_srcptr poly2, slong len2, slong n, slong prec)
{
arb_ptr a, b, c, d, e, f, w;
arb_ptr t, u, v;
slong i;
len1 = FLINT_MIN(len1, n);
len2 = FLINT_MIN(len2, n);
w = flint_malloc(sizeof(arb_struct) * (2 * (len1 + len2 + n)));
a = w;
b = a + len1;
c = b + len1;
d = c + len2;
e = d + len2;
f = e + n;
t = _arb_vec_init(n);
u = _arb_vec_init(n);
v = _arb_vec_init(n);
for (i = 0; i < len1; i++)
{
a[i] = *acb_realref(poly1 + i);
b[i] = *acb_imagref(poly1 + i);
}
for (i = 0; i < len2; i++)
{
c[i] = *acb_realref(poly2 + i);
d[i] = *acb_imagref(poly2 + i);
}
for (i = 0; i < n; i++)
{
e[i] = *acb_realref(res + i);
f[i] = *acb_imagref(res + i);
}
_arb_vec_add(t, a, b, len1, prec);
_arb_vec_add(u, c, d, len2, prec);
_arb_poly_mullow(v, t, len1, u, len2, n, prec);
_arb_poly_mullow(t, a, len1, c, len2, n, prec);
_arb_poly_mullow(u, b, len1, d, len2, n, prec);
_arb_vec_sub(e, t, u, n, prec);
_arb_vec_sub(f, v, t, n, prec);
_arb_vec_sub(f, f, u, n, prec);
for (i = 0; i < n; i++)
{
*acb_realref(res + i) = e[i];
*acb_imagref(res + i) = f[i];
}
_arb_vec_clear(t, n);
_arb_vec_clear(u, n);
_arb_vec_clear(v, n);
flint_free(w);
}
void
acb_poly_mullow_transpose_gauss(acb_poly_t res, const acb_poly_t poly1,
const acb_poly_t poly2,
slong n, slong prec)
{
slong len1, len2;
len1 = poly1->length;
len2 = poly2->length;
if (len1 == 0 || len2 == 0 || n == 0)
{
acb_poly_zero(res);
return;
}
n = FLINT_MIN((len1 + len2 - 1), n);
len1 = FLINT_MIN(len1, n);
len2 = FLINT_MIN(len2, n);
if (res == poly1 || res == poly2)
{
acb_poly_t t;
acb_poly_init2(t, n);
_acb_poly_mullow_transpose_gauss(t->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2, n, prec);
acb_poly_swap(res, t);
acb_poly_clear(t);
}
else
{
acb_poly_fit_length(res, n);
_acb_poly_mullow_transpose_gauss(res->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2, n, prec);
}
_acb_poly_set_length(res, n);
_acb_poly_normalise(res);
}