tril

Lower triangular part of a matrix

Usage

tril(X)

• X should be a numeric matrix, i.e., ndims(X) equal to 2.
• It returns the lower triangular part of X, i.e., elements below or on the main diagonal of X.
• If X is a character array, elements above the main diagonal are filled with the white-space characters.
• It returns an empty matrix if X is empty.

tril(X, k)

• k should be an integer scalar, not equal to NaN nor Inf.
• If k < 0, it returns elements below or on the k-th lower diagonal of X.
• If k > 0, it returns elements below or on the k-th upper diagonal of X.
• If k == 0, it returns the same result as tril(X).

Example

• In the following, tril() extracts the lower triangular part of a character array. The upper part is filled with spaces.

Input

a=['abcd';'efgh';'ijkl';'mnop']
tril(a)

Output

a =
abcd
efgh
ijkl
mnop

ans =
a   
ef  
ijk 
mnop