Upper triangular need to be interpreted as owning only zero entries beneath the principle diagonal, which starts with the upper still left corner. Illustration[edit] During the decrease triangular matrix all factors above the diagonal are zero, from the higher triangular matrix, all the elements underneath the diagonal are zero. http://crotchlesspanties11.fitnell.com/33085668/5-easy-facts-about-how-t-u-an-l-b-d-described