/* 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 2.1 of the License, or (at your option) any later version. See . */ #include "fmpq_mat.h" int fmpq_mat_inv(fmpq_mat_t B, const fmpq_mat_t A) { slong n = A->r; if (n == 0) { return 1; } else if (n == 1) { if (fmpq_is_zero(fmpq_mat_entry(A, 0, 0))) return 0; fmpq_inv(fmpq_mat_entry(B, 0, 0), fmpq_mat_entry(A, 0, 0)); return 1; } else if (n == 2) { fmpq_t d; int success; fmpq_init(d); fmpq_mul(d, fmpq_mat_entry(A, 0, 0), fmpq_mat_entry(A, 1, 1)); fmpq_submul(d, fmpq_mat_entry(A, 0, 1), fmpq_mat_entry(A, 1, 0)); success = !fmpq_is_zero(d); if (success) { fmpq_t t00, t01, t10, t11; fmpq_inv(d, d); fmpq_init(t00); fmpq_init(t01); fmpq_init(t10); fmpq_init(t11); fmpq_mul(t00, fmpq_mat_entry(A, 1, 1), d); fmpq_mul(t01, fmpq_mat_entry(A, 0, 1), d); fmpq_mul(t10, fmpq_mat_entry(A, 1, 0), d); fmpq_mul(t11, fmpq_mat_entry(A, 0, 0), d); fmpq_set(fmpq_mat_entry(B, 0, 0), t00); fmpq_neg(fmpq_mat_entry(B, 0, 1), t01); fmpq_neg(fmpq_mat_entry(B, 1, 0), t10); fmpq_set(fmpq_mat_entry(B, 1, 1), t11); fmpq_clear(t00); fmpq_clear(t01); fmpq_clear(t10); fmpq_clear(t11); } fmpq_clear(d); return success; } else { fmpz_mat_t Aclear, I; fmpz * den; slong i; int success; fmpz_mat_init(Aclear, n, n); fmpz_mat_init(I, n, n); den = _fmpz_vec_init(n); fmpq_mat_get_fmpz_mat_rowwise(Aclear, den, A); for (i = 0; i < n; i++) fmpz_set(fmpz_mat_entry(I, i, i), den + i); success = fmpq_mat_solve_fmpz_mat(B, Aclear, I); fmpz_mat_clear(Aclear); fmpz_mat_clear(I); _fmpz_vec_clear(den, A->r); return success; } }