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MathGroup Archive 2007

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Re: How to make a loop for this problem!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75369] Re: How to make a loop for this problem!
  • From: Ray Koopman <koopman at sfu.ca>
  • Date: Fri, 27 Apr 2007 05:20:46 -0400 (EDT)
  • References: <f0pkt5$28h$1@smc.vnet.net>

On Apr 26, 12:38 am, pskma... at googlemail.com wrote:
> Hi all,
>
> This comand:
> A = Array[Random[Integer] &, {3, 3}]
> generates a 3x3 random matrix its terms between 0 and 1.
>
> I need to make a loop that geerates a finite number of matrices, let's
> say 512 and this loop check that non of the matrices is equal to
> another one (no repeated matrices)
>
> I can geerate thoses random, matrices with this command:
> Do[Print[Array[Random[Integer] &, {3, 3}]], {512}]
> but I may have two matrices that are equal and also as far as I know I
> cann't use the out put because of the command, Print.

This will generate m different random n x n binary matrices, but
it will work only for small n's because it takes a simple-minded
approach to selecting m different random integers in Range[2^n^2].

gen[m_Integer?Positive, n_Integer?Positive] /; m <= 2^n^2 :=
Partition[#,n]& /@ IntegerDigits[ Ordering[
                  Table[Random[],{2^n^2}], m] - 1, 2, n^2]

gen[16,2]

{{{0,1},{0,0}}, {{0,0},{0,0}}, {{1,0},{1,0}}, {{1,1},{1,1}},
 {{0,0},{1,0}}, {{1,1},{0,1}}, {{0,1},{1,0}}, {{0,0},{0,1}},
 {{1,1},{1,0}}, {{0,1},{1,1}}, {{1,0},{0,0}}, {{0,1},{0,1}},
 {{1,0},{1,1}}, {{0,0},{1,1}}, {{1,1},{0,0}}, {{1,0},{0,1}}}

gen[16,5]

{{{1,0,1,0,1},{1,0,1,1,0},{1,0,0,1,1},{0,1,1,0,0},{0,0,1,0,0}},
 {{1,0,1,1,0},{1,0,0,1,0},{0,0,1,0,1},{1,0,1,0,0},{1,1,1,1,1}},
 {{1,1,1,0,0},{0,0,0,1,1},{0,0,1,1,1},{1,1,1,0,1},{0,1,1,0,0}},
 {{1,0,0,1,1},{1,1,1,0,0},{1,0,0,1,1},{1,0,0,1,1},{1,0,1,1,0}},
 {{0,1,1,1,0},{1,1,1,0,0},{1,0,1,1,0},{0,0,0,0,0},{1,0,0,0,0}},
 {{0,0,1,0,1},{1,0,1,0,0},{0,1,1,0,1},{0,0,1,0,0},{0,1,0,1,1}},
 {{0,1,0,0,1},{0,1,1,1,0},{1,1,1,0,0},{0,1,1,1,0},{0,1,1,0,1}},
 {{1,0,0,0,0},{0,1,1,1,0},{0,1,1,1,0},{0,1,0,0,0},{0,0,1,1,1}},
 {{1,0,0,0,1},{1,1,0,0,1},{0,1,0,1,0},{0,1,1,0,1},{0,0,1,0,0}},
 {{0,0,0,0,1},{0,0,1,1,1},{0,1,0,1,0},{0,0,1,0,1},{1,0,0,1,1}},
 {{1,0,1,1,1},{0,1,1,0,1},{1,1,1,1,1},{0,0,1,0,0},{0,1,0,1,0}},
 {{0,1,1,0,0},{1,1,0,0,1},{0,0,1,1,1},{0,0,0,0,1},{1,1,0,1,0}},
 {{0,1,0,0,0},{0,1,0,1,0},{1,0,1,0,0},{0,1,0,0,1},{0,1,0,1,1}},
 {{0,0,0,0,0},{1,1,1,0,0},{1,0,1,1,1},{0,0,0,0,1},{0,1,0,0,1}},
 {{0,0,1,0,0},{1,0,1,0,0},{0,0,1,1,0},{1,1,0,0,0},{1,1,1,1,0}},
 {{1,0,0,1,1},{1,0,0,0,0},{0,0,0,1,0},{1,1,0,0,0},{0,1,0,0,1}}}



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