Upper triangular must be interpreted as obtaining only zero entries under the most crucial diagonal, which starts in the upper left corner. Instance[edit] A A A B A C A D A E A File A G A H A I A J A K A L A M http://bridalandweddinglingerie58902.canariblogs.com/an-unbiased-view-of-how-t-u-an-l-b-d-11522035