MathGroup Archive 1999

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Matrix Manipulation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg16389] Matrix Manipulation
  • From: Andreas Paul Friedrich Bernhard <bernhard at eng.umd.edu>
  • Date: Thu, 11 Mar 1999 02:16:54 -0500
  • Organization: University of Maryland, College Park
  • Sender: owner-wri-mathgroup at wolfram.com

I am trying to modify the elements of a submatrix in a matrix, without
having to replace each element explicitly

for example:
mm   = { {1,2,3}, {4,5,6}, {7,8,9} }
msub      = { {21,22}, {23,24} }
I now wish to add the sub matrix: to positions (1,1),(1,3),(3,1),(3,3)

I have tried using ReplacePart but it does not recognize the
multidimensional replacement, I have also tried
mm[ {{1,3} , {1,3}} ]  = mm[ {{1,3} , {1,3}}]  + msub

but this crashes horribly


Thanks
AndyIII

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****************************************************
*   Andreas P.F. Bernhard                          *
*   Aerospace Department, University of Maryland   *
*   College Park, MD 20742                         *
*   bernhard at Glue.umd.edu                          *
*   Fax: (301) 314-9001, Tel: (301) 405-1141       *
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