Am I understanding this right? Let's say I have a 15x15 matrix called Z. Then the matrix of eigenvalues calculated from Z, called D, can have two forms - either diagonal or block diagonal. If the matrix D comes out with values only on the diagonal, then there are only real values. But, if the matrix D comes out block diagonal, then there are real and imaginary values. The only reason the matrix D comes out block diagonal is if it is not symmetric, not only in terms of dimensions, but in terms of the actual values in the original matrix Z. Correct???