triu

triu#

Signature#

nabla.triu(x: 'Array', k: 'int') -> 'Array'

Description#

Returns the upper triangular part of a matrix or batch of matrices.

The elements below the k-th diagonal are zeroed out. The input is expected to be at least 2-dimensional.

Parameters#

  • x (Array): Input array with shape (…, M, N).

  • k (int, optional): Diagonal offset. k = 0 is the main diagonal. k > 0 is above the main diagonal, and k < 0 is below the main diagonal. Defaults to 0.

Returns#

  • Array: An array with the lower triangular part zeroed out, with the same shape and dtype as x.

Examples#

>>> import nabla as nb
>>> x = nb.ndarange((3, 3), dtype=nb.DType.int32)
>>> x
Array([[0, 1, 2],
       [3, 4, 5],
       [6, 7, 8]], dtype=int32)

>>> # Upper triangle with the main diagonal
>>> nb.triu(x, k=0)
Array([[0, 1, 2],
       [0, 4, 5],
       [0, 0, 8]], dtype=int32)

>>> # Upper triangle above the main diagonal
>>> nb.triu(x, k=1)
Array([[0, 1, 2],
       [0, 0, 5],
       [0, 0, 0]], dtype=int32)
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