Matlab doesn't recognise symmetric matrix

Question

N/A 2016-10-28

回答： Walter Roberson 2016-10-28

Hi, I create various matrices in matlab and check each of them if they're symmetric or not. However when I create a matrix:

M = [5 1 3; 2 0 2; 3 1 5;]
    5 1 3
M = 2 0 2
    3 1 5

The matrix is symmetric but when I run

tf = issymmetric(M)

I still get 0 which states it's not symmetric.

What am I doing wrong here?

Thank you.

Answer 1

Walter Roberson 2016-10-28

For MATLAB purposes (as is common), "symmetric" refers to symmetric along the main diagonal.

Your candidate matrix is not symmetric along any axis: instead it is rotationally invariant for a 180 degree rotation.