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I am reading a section in a book that talks about normal matrices, and I see the following:

A normal matrix is a matrix that commutes with its adjoint,


Eh? What do the brackets and the comma inside mean?

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The notation means that $AA^{T}-A^{T}A$=0.

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It is called the commutator: – Jonas Meyer Mar 18 '11 at 6:26

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