Re: SPOG FOR THE PRACTICAL SCIENTIST

From: Stein A. Strømme (stromme@mi.uib.no)
Date: Wed Jul 11 2001 - 04:22:04 EDT

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    George Hammond <ghammond@mediaone.net> writes:

    > Stein A. Strømme wrote:
    > >
    > > A 1000x1000 real symmetric matrix always admits 1000 linearly
    > > independent eigenvectors. This is the well known result that is
    > > referred to here.
    >
    > [Hammond]
    > I hope you're not intent on playing mathematical trivia
    > with me.. I'm not interested in trivia. In general the
    > "rank" of a matrix is not the same thing as the "order"
    > of a matrix.

    I suppose the explanation is that you are talking about a 1000x1000
    real symmetric matrix of rank 13. In that case there are only 13
    *non-zero eigenvalues* (counted with the proper multiplicity). If
    these are all distinct, then there will be 13 one-dimensional
    eigenspaces (and one 987-dimensional eigenspace). Then you need to make
    a choice of eigenvector in each of the 13 one-dimensional subspaces in
    order to arrive at a set of 13. Is this what you mean?

    > An NxN matrix is by definition of order N,
    > however the rank of the matrix may be much less than N.
    > The rank of the matrix is the number of eigenvectors
    > (independent eigenvalues) of the matrix.

    No, as explained above. The rank is the number of non-zero
    eigenvalues.

    Stein

    --
    http://www.mi.uib.no/~stromme
    



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