Return upper triangular part of symbolic matrix
triu(A) returns a triangular matrix that retains the upper
part of the matrix A. The lower triangle of the resulting matrix
is padded with zeros.
Display the matrix retaining only the upper triangle of the original symbolic matrix:
syms a b c A = [a b c; 1 2 3; a + 1 b + 2 c + 3]; triu(A)
ans = [ a, b, c] [ 0, 2, 3] [ 0, 0, c + 3]
Display the matrix that retains the elements of the original symbolic matrix on and above the first superdiagonal:
syms a b c A = [a b c; 1 2 3; a + 1 b + 2 c + 3]; triu(A, 1)
ans = [ 0, b, c] [ 0, 0, 3] [ 0, 0, 0]
Display the matrix that retains the elements of the original symbolic matrix on and above the first subdiagonal:
syms a b c A = [a b c; 1 2 3; a + 1 b + 2 c + 3]; triu(A, -1)
ans = [ a, b, c] [ 1, 2, 3] [ 0, b + 2, c + 3]