tril

tril(m, k=0)

Lower triangle of an array.

Return a copy of an array with elements above the k-th diagonal zeroed.

Parameters:

m : ndarray, shape (M, N)

Input array.

k : int, optional

Diagonal above which to zero elements. k = 0 (the default) is the main diagonal, k < 0 is below it and k > 0 is above.

Returns:

tril : ndarray, shape (M, N)

Lower triangle of m, of same shape and data-type as m.

See also

triu

same thing, only for the upper triangle

Examples

>>> a = np.array([[1,2,3],[4,5,6],[7,8,9],[10,11,12]])
>>> np.tril(a, -1)
array([[ 0.,  0.,  0.],
       [ 4.,  0.,  0.],
       [ 7.,  8.,  0.],
       [10., 11., 12.]])