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Matrix multiply

  1. Jul 27, 2008 #1
    Thank you
    1. What is the value of the following matrix multiplication




    2. [tex]A^{-1}DA^{T}=?[/tex]
    D is diagonal matrix





    3. and how to find D to make [tex]a_i C Z[/tex]


    4. [tex]A^{-1}DA^{T}[/tex]


    [tex]a_i[/tex] is elements of [tex]A^{-1}[/tex]
    My head really aches, please help
     
    Last edited: Jul 27, 2008
  2. jcsd
  3. Jul 27, 2008 #2
    C is "belongs to" Z, I mean

    I can't write a \belongto
     
  4. Jul 27, 2008 #3

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    You want the components of A-1 integers? I'm not sure what your question is. If the components of A itself are integers and A has determinant = 1, then the components of A-1 are integers. D has nothing to do with that- especially since you haven't told us anything about ADA-1. Is there some condition on that?

    Oh, and [itex]a_n \in Z[/itex] is written [ itex ] a_n\in Z[ /itex ], without the spaces, of course.
     
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