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/*
Copyright (C) 2011 Fredrik Johansson
This file is part of FLINT.
FLINT 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 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpz_poly.h"
#include "fmpz_poly_mat.h"
void
fmpz_poly_mat_mullow(fmpz_poly_mat_t C, const fmpz_poly_mat_t A,
const fmpz_poly_mat_t B, slong len)
{
slong ar, bc, br;
slong i, j, k;
fmpz_poly_t t;
ar = A->r;
br = B->r;
bc = B->c;
if (br == 0 || len < 1)
{
fmpz_poly_mat_zero(C);
return;
}
if (C == A || C == B)
{
fmpz_poly_mat_t T;
fmpz_poly_mat_init(T, ar, bc);
fmpz_poly_mat_mullow(T, A, B, len);
fmpz_poly_mat_swap_entrywise(C, T);
fmpz_poly_mat_clear(T);
return;
}
fmpz_poly_init(t);
for (i = 0; i < ar; i++)
{
for (j = 0; j < bc; j++)
{
fmpz_poly_mullow(fmpz_poly_mat_entry(C, i, j),
fmpz_poly_mat_entry(A, i, 0),
fmpz_poly_mat_entry(B, 0, j), len);
for (k = 1; k < br; k++)
{
fmpz_poly_mullow(t, fmpz_poly_mat_entry(A, i, k),
fmpz_poly_mat_entry(B, k, j), len);
fmpz_poly_add(fmpz_poly_mat_entry(C, i, j),
fmpz_poly_mat_entry(C, i, j), t);
}
}
}
fmpz_poly_clear(t);
}