Is it the case that the computation of the value for the entity in the second iteration of your loop requires the value of the entity computed during the first iteration of your loop? Something like this basic scenario?
n = 5;
x = ones(1, n);
for k = 2:n
x(k) = (x(k-1).^2)+1
end
If so you can't use parfor because your loop iterations are not independent. You must compute the value of x(4) before it is possible for you to compute the value of x(5) in the example above, for instance.
Now the question of whether or not it's possible to speed up your code is a different matter entirely. We can't offer any firm guidance on that because you haven't shown us your code, but you can use the tools for measuring and profiling your code listed on this documentation page along with Code Analyzer to try to identify bottlenecks and/or suggested improvements in your code.
