Binary Search Using Threshold

Question

I have an ordered list that I am trying to search but am not looking for a specific value in the list. I have a threshold and want to find all the values greater than that value.

For example, if I have the list 2 4 6 8 10 12 14 16 18 20, I'd be searching for the index that returns me all the values greater than a specific number like 13.

Here is what my code looks like, but it isn't working properly for all cases. For example, if I have a list of 2 20 and looking for numbers bigger than 10 the code gets stuck. I'm trying to find an elegant solution to these problem without adding in a bunch of if loops to check for specific cases as I will be running this function 10 million times on lists up to 8! long, so efficiency is key. Any suggestions would be appreciated.

% Note that permutations represents my ordered list of values

function [index] = binarySearch(permutations, threshold) 
    start = 1;
    stop = length(permutations);
    middle = floor((stop+start)/2);
    while(stop-start > 0)
        if(permutations(middle) > threshold)
            stop = middle;
        elseif(permutations(middle) < threshold)
            start = middle;
        elseif(permutations(middle) == threshold)
            index = middle;
            return;
        end
        if(stop == 1)
            index = 0;
            return;
        end
        middle = floor((stop+start)/2);
    end
    index = middle;
end