Transform an upper triangular matrix MATLAB

Question

If I have an upper triangular matrix on MATLAB LIKE

A =

    1 2 3 4
    0 5 6 7
    0 0 8 9
    0 0 0 1

How would you convert it to:

Answer 1

a = A + triu(A, 1)' does what you want (assuming real matrices or you want a Hermitian matrix for complex values).