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Jordan Matrix Decomposition

  1. Sep 11, 2011 #1
    A = PD[P][/-1];
    A: square matrix;
    D: is a matrix of Jordan canonical form
    P:is EigenVectors..(p1,p2,p3,p4....pr)

    Is it possible to permute the sequence p1,p2,p3,p4....pr into other form???
    I know it should be possible to permute...
    How should permute it and what significance it has?
    Why is it essential to permute vectors/matrix?
    Thanks in advance for your attention.
  2. jcsd
  3. Sep 11, 2011 #2


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    Science Advisor

    If an n by n matrix is "diagonalizable", that means it has n independent eigenvectors and so if you use those eigenvectors as basis vectors will give a diagonal matrix representing the same linear transformation as the original matrix- the two matrices are "similar". Changing the order in which you use the eigenvectors will give a diagonal matrix with the number on the diagonal in different places, but they will still be similar to the original matrix and so to each other.

    If a matrix is not diagonalizable, it does not have a "complete set" of eigenvectors- you can not have a basis for the vector space consisting entirely of eigenvetors. But you can, by using "generalized eigenvectors" (v is a "generalized eigenvector" corresponding to eigenvalue [itex]\lambda[/itex] if it is NOT true that [itex]Av= \lambda v[/itex] but it is true that Av is an eigenvalue or another generalized eigenvector.) The eigenvector and generalized eigenvectors corresponding to a given eigenvalue give the "Jordan" blocks in the Jordan Normal form. Changing the order of those will give a matrix with the rows and columns rearranged and so not in "Jordan Normal Form", but still "similar" to such a matrix.
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