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Re: Replacement rules for large matrixes

  • To: mathgroup at smc.vnet.net
  • Subject: [mg119838] Re: Replacement rules for large matrixes
  • From: dr DanW <dmaxwarren at gmail.com>
  • Date: Sat, 25 Jun 2011 05:27:05 -0400 (EDT)
  • Reply-to: comp.soft-sys.math.mathematica at googlegroups.com

Is your matrix a nested list or a SparseArray[]?  From your description, I am guessing it is a nested list.  Try working with your matrix as a SparseArray[] instead.

Next problem: Replace[] does not work on SparseArray[]'s.  However, you can use BlockRules[] (code below) to do the replacement.

Code for BlockRules[] by Andrew Moylen at Wolfram, from an earlier posting on this group that I can't find right now:

SetAttributes[BlockRules, HoldRest]; 

BlockRules[rules_, expr_] := Block @@ Append[Apply[Set, Hold[rules], {2}], 
    Unevaluated[expr]]

Enjoy,
Daniel


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