doc knnsearch
If you have the Statistics Toolbox this sounds like your magic command.
Of course, if you just need a magic command, you can always run:
magic(5)
More Using knnsearch here is probably overkill when you could just use a for-loop, finding the minimum of the exclusive set. But here is how I would do this with knnsearch:
[idx,D] = knnsearch(values',values','K',2) %Get two because the first will be the value itself
idx(:,2) %2nd column is the closest one that isn't the same
D(:,2) %Distance
values(idx(:,2)) %What was the original value?
