THE DETERMINANT
Definition
Definition: Let A = [aij] be an n x n matrix. The determinant function, denoted by det, is defined by
det(A) = $ \sum{(a1j1 a2j2... anjn)} $
where the summation is over all permutations j1, j2... jn of the set S = {1, 2, ..., n}. The sign is taken as + or - according to whether the permutation j1, j2, ... jn is even or odd.