how to mex this recursion

I am running a large program and a small function is taking up all the computing time, I havent been able to use the automatic c coder app because the function is recursive - what can I do ?

function f = fF(M1,M2,Integer)

%initialize to zero
TheSum = 0;

%loop with recursion
for n=1:(Integer-1)
   TheSum = M1(Integer,n)*fF(M1,M2,n);
end

%puts output together
f = M2(:,Integer)-TheSum;

end

M1 and M2 are matrices, Integer is an Integer :)

[John D'Errico]

Just creating a mex from this will not magically make it more efficient.

Instead, think about WHY it is spending so much time. We cannot really know anything, since you have told us nothing of value. What are these numbers? Just telling us they are integers is silly. 1 is an integer, so is zero. But your code will likely run quickly if Integer is 0 or 1. Tell us the actual values.

The crystal ball is so foggy.

Answer 1

[Walter Roberson]

Your lines

for n=1:(Integer-1)
  TheSum = M1(Integer,n)*fF(M1,M2,n);
end

can be written less recursively as

TheSum = M1(Integer, Integer-1) * fF(M1, M2, Integer-1) ;

with no loop. Are you sure that was your intention?

What is the purpose of your routine? It reminds me of calculating determinants.