void
fmpz_mat_solve_cramer(fmpz * x, fmpz_t den, const fmpz_mat_t A, const fmpz * b)
{
long dim = A->r;
switch (dim)
{
case 0:
fmpz_set_ui(den, 1UL);
break;
case 1:
fmpz_set(den, A->rows[0]);
fmpz_set(x, b);
break;
case 2:
_fmpz_mat_solve_cramer_2x2(x, den, A->rows, b);
break;
case 3:
_fmpz_mat_solve_cramer_3x3(x, den, A->rows, b);
break;
default:
printf("Exception: fmpz_mat_solve_cramer: dim > 3 not implemented");
abort();
}
}
int
fmpz_mat_solve_cramer(fmpz_mat_t X, fmpz_t den,
const fmpz_mat_t A, const fmpz_mat_t B)
{
long i, dim = fmpz_mat_nrows(A);
if (dim == 0)
{
fmpz_one(den);
return 1;
}
else if (dim == 1)
{
fmpz_set(den, fmpz_mat_entry(A, 0, 0));
if (fmpz_is_zero(den))
return 0;
if (!fmpz_mat_is_empty(B))
_fmpz_vec_set(X->rows[0], B->rows[0], fmpz_mat_ncols(B));
return 1;
}
else if (dim == 2)
{
fmpz_t t, u;
_fmpz_mat_det_cofactor_2x2(den, A->rows);
if (fmpz_is_zero(den))
return 0;
fmpz_init(t);
fmpz_init(u);
for (i = 0; i < fmpz_mat_ncols(B); i++)
{
fmpz_mul (t, fmpz_mat_entry(A, 1, 1), fmpz_mat_entry(B, 0, i));
fmpz_submul(t, fmpz_mat_entry(A, 0, 1), fmpz_mat_entry(B, 1, i));
fmpz_mul (u, fmpz_mat_entry(A, 0, 0), fmpz_mat_entry(B, 1, i));
fmpz_submul(u, fmpz_mat_entry(A, 1, 0), fmpz_mat_entry(B, 0, i));
fmpz_swap(fmpz_mat_entry(X, 0, i), t);
fmpz_swap(fmpz_mat_entry(X, 1, i), u);
}
fmpz_clear(t);
fmpz_clear(u);
return 1;
}
else if (dim == 3)
{
return _fmpz_mat_solve_cramer_3x3(X, den, A, B);
}
else
{
printf("Exception: fmpz_mat_solve_cramer: dim > 3 not implemented");
abort();
}
}
