What does fidelity mean?

Can some body explain the following formula?

Answer 1

[Walter Roberson]

%mu says whether the E values bear the same relationship to each other that the M values do
mu(i,j) = sign( E(D(i)) - E(D(j)) ) == sign( M(D(i)) - M(D(j)) )

However, we do not have enough information about the meaning of E or M to fully optimize the computation. I suspect it might be possible to do all of the comparisons at the same time over an array, zero the diagonal, sum the result, divide by n*(n-1), multiply by 100 -- the 2 would cancel in such an implementation, I think.

mu = sign(bsxfun(@minus, E(:), E(:).')) == sign(bsxfun(@minus, M(:), M(:).'));
n = size(mu,1);
mu(1:n+1:end) = 0;   %zero diagonal
F = 100 * sum(mu(:)) / (n*(n+1));

[Student new]

Sorry i forgot to mention. E is estimated and M is measured value. D is set of implementation. I was looking for a theoratical explanation but could not find one. Thanks again.

[Walter Roberson]

Well theoretical explanations are not suitable topics for MATLAB Answers, which is about MATLAB, so here you get an implementation or you get your question closed as being off topic.