58 lines
1.5 KiB
Matlab
58 lines
1.5 KiB
Matlab
function [ SigmaInv] = CalcSigmaCCNFflat(alphas, betas, n, precalcQ2withoutBeta, precalc_eye, precalc_zeros)
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%CALCSIGMAPRF Summary of this function goes here
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% Detailed explanation goes here
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% constructing the sigma
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% A = zeros(n);
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%
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% for i=1:n
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%
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% A(i,i) = alphas' * mask(i,:)';
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%
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% end
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% this is simplification of above code
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% if(useIndicators)
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% A = diag(mask * alphas);
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% else
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% A = sum(alphas) .* eye(n);
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A = sum(alphas) .* precalc_eye;
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% A = sum(alphas) * eye(n);
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% not faster
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% a = mtimesx(sum(alphas), eye(n), 'SPEED');
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% a2 = mtimesx(sum(alphas), eye(n), 'SPEEDOMP');
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% end
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% calculating the B from the paper
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% for i=1:n
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% for j=1:n
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%
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% if(i == j)
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% q2(i,j) = beta * (sum(S(i,:)) - S(i,i));
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% else
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% q2(i,j) = -beta * S(i,j);
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% end
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% end
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% end
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% the above code can be simplified by the following lines of code
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% using the precalculated lower triangular elements of B without beta
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Btmp = precalcQ2withoutBeta * betas;
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% not faster
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% Btmp = mtimesx(precalcQ2withoutBeta, betas, 'SPEED');
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% Btmp = mtimesx(precalcQ2withoutBeta, betas, 'SPEEDOMP');
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% now make it into a square symmetric matrix
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% B = zeros(n,n);
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B = precalc_zeros;
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on = tril(true(n,n));
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B(on) = Btmp;
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B = B';
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B(on) = Btmp;
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SigmaInv = 2 * (A + B);
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end
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