From tzukuoh at cs.cmu.edu  Tue Dec 30 22:29:08 2008
From: tzukuoh at cs.cmu.edu (Tzu-Kuo Huang)
Date: Tue, 30 Dec 2008 22:29:08 -0500
Subject: [Research] A question on a matrix equation
Message-ID: <001c01c96af7$f0cddf20$d2699d60$@cmu.edu>

Dear all,

 

Recently I came across a matrix equation:

 

QQ' = Q'Q

 

where Q is a square matrix and Q' is its transpose.

This equation is satisfied when Q is symmetric or orthogonal.

My question is: Can this equation be satisfied by a Q that is not symmetric
nor orthogonal?

Any thoughts, pointers, or suggestions are appreciated!

 

Many thanks,

TK

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