(data structure)

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

**Generalization** (I am a kind of ...)

*matrix*.

**Specialization** (... is a kind of me.)

*strictly lower triangular matrix*.

**See also**
*upper triangular matrix*, *ragged matrix*.

*Note:
For example *

j | ||||
---|---|---|---|---|

i | 1 | - | - | - |

7 | 7 | - | - | |

1 | 0 | 1 | - | |

1 | 9 | 5 | 4 |

* 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

Go to the Dictionary of Algorithms and Data Structures home page.

If you have suggestions, corrections, or comments, please get in touch with Paul E. Black.

Entry modified 17 December 2004.

HTML page formatted Fri Mar 25 16:20:34 2011.

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: http://www.nist.gov/dads/HTML/lowerTriangularMatrix.html