909
909
The default value of @var{k} is zero, so that @code{triu} and
910
910
@code{tril} normally include the main diagonal as part of the result.
912
If the value of @var{k} is nonzero integer, the selection of elementsstarts at an offset of @var{k} diagonals above or below the maindiagonal; above for positive @var{k} and below for negative @var{k}.
916
913
The absolute value of @var{k} must not be greater than the number of
917
914
sub-diagonals or super-diagonals.