How i can create random array with fixed sum for each row and column?

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Accepted Answer

Roger Stafford
Roger Stafford on 20 Aug 2014
Edited: Roger Stafford on 20 Aug 2014
I assume by "rounded off" you mean the elements are all to be integers. Do this:
A = zeros(4);
for k = 1:7
p = randperm(4); % <-- This is the source of randomness
for ix = 1:4
A(p(ix),ix) = A(p(ix),ix) + 1;
end
end
A = [A(:,1),zeros(4,1),A(:,2:4)]; % Insert a column of four zeros
A = [A(1:3,:);zeros(1,5);A(4,:)]; % Insert a row of five zeros
A(1,1) = 0; A(3,3) = 0; A(5,5) = 0; % Set non-zero diagonal elements to 0
A should be a randomly created 5 x 5 matrix whose elements are all integers ranging from 0 to 7 in such a way that
1) row 1 and column 1 have equal sums,
2) row 2 has a sum of 7 and column 2 has a sum of 0,
3) row 3 and column 3 have equal sums,
4) row 4 has a sum of 0 and column 4 has a sum of 7,
5) row 5 and column 5 have equal sums,
6) its diagonal elements are all zeros, and
7) all column and row sums are 7 or less,

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