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MathGroup Archive 1993

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matrix manipulation using transformations

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: matrix manipulation using transformations
  • From: Michael Carter <ECON076 at cantva.canterbury.ac.nz>
  • Date: Tue, 01 Jun 1993 15:44:43 +1200

I am trying to write some matrix manipulations using patterns and 
transformations. Can any one help me understand the following:

For example to divide each row by its last element, this works fine
for row 2:
        m /. m[[2]] :> m[[2]] / m[[2,3]]

but replacing 2 by k doesn't. 

       m /. m[[k_]] :> m[[k]] /m[[k,3]]

yielding the error messages:
Part::pspec: 
   Part specification k_
     is neither an integer nor a list of non-zero
     integers.
Part::pspec: 
   Part specification k_
     is neither an integer nor a list of non-zero
     integers.

I think I can understand why Mma might treat 2 and k differently; but is 
there an elegant way to do what I want??

Michael Carter

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Michael Carter                      m.carter at csc.canterbury.ac.nz

Department of Economics             voice: + 64 3 364 2524
University of Canterbury            fax:   + 64 3 364 2635
Private Bag 4800
Christchurch
NEW ZEALAND


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