Symbolic Math Toolbox™

triu - Symbolic upper triangle

Syntax

triu(X)
triu(X, K)

Description

triu(X) is the upper triangular part of X.

triu(X, K) returns an upper triangular matrix that retains the elements of X on and above the k-th diagonal and sets the remaining elements to 0. The values k=0, k>0, and k<0 correspond to the main, superdiagonals, and subdiagonals, respectively.

Examples

Suppose

A =
[   a,   b,   c ]
[   1,   2,   3 ]
[ a+1, b+2, c+3 ]

Then triu(A) returns

[   a,   b,   c ]
[   0,   2,   3 ]
[   0,   0, c+3 ]

triu(A,1) returns

[ 0, b, c ]
[ 0, 0, 3 ]
[ 0, 0, 0 ]

triu(A,-1) returns

[   a,   b,   c ]
[   1,   2,   3 ]
[   0, b+2, c+3 ]

See Also

diag, tril

tril

uint8, uint16, uint32, uint64