How do I create a series of permutation matrices

Hi all,

I'm new, and my maths isn't great. Was wondering if anyone could help me..

I want to create a series of matrices (zeros(3,3)) that show all possible combinations of making 1-6 of the 9 values a 1.

Mathematically, this should produce; 9nCr1 = 9 + 9nCr2 = 36 + 9nCr3 = 84 + 9nCr4 = 126 + 9nCr5 = 126 + 9nCr6 = 84 = 465 separate matrices

Does anyone know how to do that without manually specifying all of them?

Answer 1

[Andrei Bobrov]

a = dec2bin(0:511,9) - '0';
n = sum(a,2);
out = reshape(a(n <= 6 & n >= 1,:).',3,3,[]);

ADD

a = dec2bin(0:511,9) - '0';
n = sum(a,2);
out = reshape(a(n <= 6 & n >= 1 & all(a(:,[1:4:9])==0,2),:).',3,3,[]);

[Josh]

Andrei Bobrov, you are a hero!

[Josh]

Sorry for a follow up - but now I want to remove any matrices where (1,1,:) + (2,2,:) + (3,3,:) > 0.

I have tried the following but it doesn't work;

a = dec2bin(0:511,9) - '0';
n = sum(a,2);
out = reshape(a(n <= 6 & n >= 1,:).',3,3,[]);

for j = 1:length(out)
  if (out(1,1,j) + out(2,2,j) + out(3,3,j)) > 0
      out(:,:,j) = [];
  end
end

Josh

[José-Luis]

+1 I would have never understood what Josh meant.

[Andrei Bobrov]

see ADD

[Josh]

Thanks!!