Upper triangular really should be interpreted as possessing only zero entries down below the primary diagonal, which begins within the higher remaining corner. Example[edit] If a sq., invertible matrix has an LDU (factorization with all diagonal entries of L and U equal to 1), then the factorization is exclusive.[5] http://remingtonddgdz.jaiblogs.com/19224588/an-unbiased-view-of-how-t-u-an-l-b-d