27 lines
578 B
Mathematica
27 lines
578 B
Mathematica
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clear;
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n = 1000;
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x = randperm(n);
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gs = 450;
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group1 = x(1:gs);
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group2 = x(gs+1:end);
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p_group1 = 0.5;
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p_group2 = 0.4;
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p_between = 0.1;
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A(group1, group1) = rand(gs, gs) < p_group1;
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A(group2, group2) = rand(n-gs, n-gs) < p_group2;
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A(group1, group2) = rand(gs, n-gs) < p_between;
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% no group2, group1 needed since we'll force the matrix to be symmetric
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A = triu(A,1); % upper triangular part of A without diagonal
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A = A + A'; % make it symmetric
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deg = sum(A);
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L = diag(deg) - A;
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[V, D] = eig(L);
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display(D(2,2));
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plot(sort(V(:,2)), '.-');
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[ignore, p] = sort(V(:,2));
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spy(A(p,p));
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