Re: SPOG FOR THE PRACTICAL SCIENTIST

From: gordon brown (gbrown@euclid.colorado.edu)
Date: Thu Jul 12 2001 - 10:57:14 EDT

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    On Wed, 11 Jul 2001, George Hammond wrote:

    > No, in general the Rank (R) of an NxN matrix is not the
    > same as the Order of the matrix which is by definition, N.
    > The number of evigenvalues and eigenvectors is equal
    > to the Rank, not the Order. Naturally these R eigenvectors
    > are non-zero or we wouldn't be talking about them. If you
    > want to insist that there are actually N, but N-R of them
    > are "zero eigenvectors", ok, but like I said I'm not here
    > to jawbone about trivia.

    George,

    The rank of a matrix is the dimension of the space spanned by its columns
    (or, equivalently, by its rows). In the special case of a diagonal matrix
    this would be the number of non-zero columns (or rows), i. e. the number
    of NON-ZERO eigenVALUES counted with multiplicity. Thus, for a
    diagonalizable matrix (such as a real symmetric matrix) the rank is also
    the number of non-zero eigenvalues counted with multiplicity.

    You seem to have eigenvectors and eigenvalues confused in your discussion.

    Gordon Brown
    Department of Mathematics
    University of Colorado
    Boulder, CO 80309-0395



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