Size is the number of row or column of a square matrix
(<=> (Size ?M) (And (Square-Matrix ?M) (= ?N (Row-Dimension ?M))))
(=> (Size $X $Y) (Square-Matrix $X))
(=> (= (Size ?M) ?N) (= ?N (Row-Dimension ?M)))
(=> (= (Size ?M) ?N) (Square-Matrix ?M))
(=> (And (Square-Matrix ?M))
(= (Determinant ?M)
(Cond ((= 1 (Size ?M)) (Value ?M 1 1))
((< 1 (Size ?M))
(Summation (Lambda (?J)
(* (Value ?M 1 ?J)
(Cofactor ?M 1 ?J)))
1
(Size ?M))))))
(=> (= (Cofactor ?M ?I ?J) ?Cof) (< 1 (Size ?M)))