tril lower triangular part of matrix

## Syntax

    tril(x [,k])

## Arguments

x

  matrix (real, complex, polynomial, rational)

k

  integer (default value 0)

## Description

Lower triangle part of a matrix. `tril(x,k)` is made by entries below the kth diagonal : k>0 (upper diagonal) and k<0 (diagonals below the main diagonal).

## Examples

    s=poly(0,'s');
    tril([s,s;s,1])
    tril([1/s,1/s;1/s,1])

## See also

- triu
- ones
- eye
- diag