# tril

## Purpose

Lower triangular part of a matrix.

## Synopsis

    L = tril(X)
    L = tril(X,k)

## Description

`tril(X)` is the lower triangular part of `X`.

`tril(X,k)` is the elements on and below the `k`-th diagonal of `X`. `k = 0` is the main diagonal, `k > 0` is above the main diagonal, and `k < 0` is below the main diagonal.

## Examples

`tril(ones(4,4),-1) is`

        0    0    0    0
        1    0    0    0
        1    1    0    0
        1    1    1    0

## See Also

    diag, triu

(c) Copyright 1994 by The MathWorks, Inc.