scipy.linalg.tril

scipy.linalg.tril(m, k=0)

Make a copy of a matrix with elements above the k-th diagonal zeroed.

Parameters :

m : array_like

Matrix whose elements to return

k : integer

Diagonal above which to zero elements. k == 0 is the main diagonal, k < 0 subdiagonal and k > 0 superdiagonal.

Returns :

tril : ndarray

Return is the same shape and type as m.

Examples

>>> from scipy.linalg import tril
>>> tril([[1,2,3],[4,5,6],[7,8,9],[10,11,12]], -1)
array([[ 0,  0,  0],
       [ 4,  0,  0],
       [ 7,  8,  0],
       [10, 11, 12]])