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Matrix Inverse needs notion of Adjoint

2012-02-15
2013-04-24
  • Rick Pingry
    Rick Pingry
    2012-02-15

    Hi, thanks for the great article!

    I was trying to derive the matrix inverse for the 3x3 and 4x4 and I kept having problems.  I was following with your statement:
    "Each element of the inverse is the determinant of its minor divided by the determinant of the whole."  That was not giving me at all what you had.  I did some more research and found this notion of "Adjoint", here http://easycalculation.com/matrix/inverse-matrix-tutorial.php

    That made all the difference.  It seems you left that part out.

    Thanks again,
    - Rick Pingry

     
  • Martin Baker
    Martin Baker
    2012-02-15

    Rick,

    Thanks very much for letting me know about this, I have changed the wording and updated the site.

    I think I really need to do some follow up things to improve the page, such as adding definitions for terms like 'minor', 'cofactor' and 'adjoint'. Also I think I really need to check all the formulas and calculators to make sure I have not made the same omission with these.

    Thanks,

    Martin