lower triangular matrix

(data structure)

Definition: A matrix that is only defined at (i,j) when i ≥ j.

Generalization (I am a kind of ...)

Specialization (... is a kind of me.)
strictly lower triangular matrix.

See also upper triangular matrix, ragged matrix.

Note: For example

i 1---

It may be more compactly represented in an array by storing entry (i,j) in location i(i-1)/2 + j (one-based indexing).

Author: PEB


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Entry modified 17 December 2004.
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Cite this as:
Paul E. Black, "lower triangular matrix", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed., U.S. National Institute of Standards and Technology. 17 December 2004. (accessed TODAY) Available from:

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