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Re: Matrix question


Needs["DiscreteMath`Combinatorica`"]

randommatrix[n_, p_] :=
  Module[{worklist, numones = Floor[p n^2]},
    worklist = Join[Array[1 &, numones], Array[0 &, n^2 - numones]];
    worklist = Part[worklist, Ordering[RandomPermutation[n^2]]];
    Partition[worklist, n]]

randommatrix[4, 0.5] // MatrixForm

First I made an array of the required number of 1's join to the remainder
zeros. Then I made a random permutation of the list. Then I partitioned the
list into rows.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/



From: sandog [mailto:sandog at mail.gr]
To: mathgroup at smc.vnet.net


i want to create a NxN matrix with zeros but i want a percentage of the
matrix spots to be one at random spots any idea? cause i have no clue how to
do that.
Any help appreciated thx .





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