u = triu(X)
u = triu(X,k)
triu(X)
is the upper triangular part of X
.
triu(X,k)
is the element on and above the k
-th diagonal of X
. k = 0
is the main diagonal, k > 0
is above the main diagonal, and k < 0
is below the main diagonal.
triu(ones(4,4),-1) is
1 1 1 1
1 1 1 1
0 1 1 1
0 0 1 1
diag
,tril
(c) Copyright 1994 by The MathWorks, Inc.