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Topic: How to inform Matlab that a matrix is symmetric.
Replies: 0

 S.K.Mody Posts: 31 Registered: 12/13/04
How to inform Matlab that a matrix is symmetric.
Posted: Mar 10, 2013 3:49 PM

On one occasion (I don't remember the exact circumstance), when was editiing a .m file, Matlab detected an expression whose effective result was X'*X. It helpfully suggested that I replace the expression by X'*X so that it could be guaranteed symmetric. I took this to mean that Matlab stores a flag in its internal matrix representation whose truth implies symmetry. Is there any Matlab documentation as to when an expression results in a matrix that is regarded by Matlab as symmetric?

If I know that the result (S) of a certain calculation must be symmetric (upto rounding error), then how should I tell Matlab that S is symmetric? For example, if I wrote:
S = (S+S')/2
or
S = max(S, S')
would this be sufficient?

Thank you,

Best Regards,