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/*
Copyright (C) 2014 Abhinav Baid
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.h"
#include "fmpz_mat.h"
void fmpz_mat_gram(fmpz_mat_t B, const fmpz_mat_t A)
{
slong i, j, k;
if (B->r != A->r || B->c != A->r)
{
flint_throw(FLINT_ERROR, "(fmpz_mat_gram): Incompatible dimensions.\n");
}
if(B == A) {
fmpz_mat_t t;
fmpz_mat_init(t, B->r, B->c);
fmpz_mat_gram(t, A);
fmpz_mat_swap_entrywise(B, t);
fmpz_mat_clear(t);
return;
}
if(A->c == 0) {
fmpz_mat_zero(B);
return;
}
for(i = 0; i < B->r; i++) {
for(j = 0; j < B->c; j++) {
fmpz_mul(fmpz_mat_entry(B, i, j),
fmpz_mat_entry(A, i, 0),
fmpz_mat_entry(A, j, 0));
for (k = 1; k < A->c; k++) {
fmpz_addmul(fmpz_mat_entry(B, i, j),
fmpz_mat_entry(A, i, k),
fmpz_mat_entry(A, j, k));
}
}
}
}