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Make a triangular matrix from a square matrix

  1. Feb 3, 2013 #1
    dear users
    I have a problem in finding eigenvalues of a 12*12 because the 12*12 matrix is so complicated
    so i decided to first make my 12*12 matrix in form of upper triangular form but I dont know how can I do it with matlab or mathematica?
    can you please tell me that what is the formula in matlab or mathematica for make an upper triangular matrix from my own 12*12 matrix?

    thanks alot
  2. jcsd
  3. Feb 3, 2013 #2

    If you need to get the eigenvalues/eigenvectors, why don't you use the corresponding function, instead making the matrix diagonal?

    Just thinking ...

  4. Feb 3, 2013 #3
    matlab and mathematica couldnt do it.matrix is very complex for these softwares and they cannot calculate eigenvalues of matrix
  5. Feb 3, 2013 #4
  6. Feb 3, 2013 #5
    thank you for your guide but my matrix which I want to find its eigenvalue is symbolic and qr is for numeric matrix.

    these are mathematica's and matlab's files of my matrix so that you can have a look on it.
    thank you alot

    Attached Files:

    • email.m
      File size:
      1.9 KB
    • email.nb
      File size:
      14.3 KB
    Last edited: Feb 3, 2013
  7. Feb 13, 2013 #6
    You want the symbolic solution for the eigenvalues of a 12x12 matrix?!

    That would be a nightmare!

    As far as I know, the various methods of computing eigenvalues--QR Decomposition, Characteristic Polynomial, etc.--are all pretty complicated. Perhaps the solutions of a 3x3 matrix would be nice concise answers. However, the solutions of a 12x12 matrix sure would not be.
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