Triangular matrix

In mathematics, a triangular matrix is a matrix with entries that have elements either completely above (upper triangular) or completely below (lower triangular) the principal diagonal.

For example:

${\begin{pmatrix}1&4&20&3&40&0&1\end{pmatrix}}$

is upper triangular and

${\begin{pmatrix}1&0&02&8&04&9&7\end{pmatrix}}$

is lower triangular.

See also: Row echelon form

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