Campus Livre
triu
Upper triangular part of a matrix.
Category: Mathematics > Linear Algebra
Syntax
U = triu(A)Keeps the main diagonal and everything above it; the rest becomes zero.
U = triu(A, k)Keeps the elements on and above the k-th diagonal.
Description
triu(A) zeroes the elements below the main diagonal. With k = 1 the diagonal is removed too, leaving the strictly upper part.
The matrix need not be square. For a wide or tall matrix the diagonal is still the set of positions (i, i + k).
Input arguments
A- Matrix (any class).
k- Integer diagonal offset:
0is the main diagonal, positive values are above it, negative values below. Default0.
Output arguments
U- Matrix of the same size and class as
A.
Example
Upper part with offsets
A = magic(3);
triu(A)
triu(A, 1)Output
ans = 3×3
8 1 6
0 5 7
0 0 2
ans = 3×3
0 1 6
0 0 7
0 0 0