How can i remove for loops?

I'm trying to remove for loops from a code I wrote long time ago.

 function [Rup] = updateR(A,E,S) 
  [imax,jmax,zmax] = size(A);
  for z = 1 : zmax

      Stmp = S(:,:,setdiff(1:zmax,z));    
      Atmp = A(:,:,setdiff(1:zmax,z));
      Etmp = E(:,:,:,:,setdiff(1:zmax,z));

      for i = 1 : imax
          for j = 1 : jmax

              sumtmp = permute(sum(sum(Etmp(i,j,:,:,:), 3), 4),[1 2 5 3 4]);
              beta = (Stmp(i,j,:)+Atmp(i,j,:)+sumtmp);

              n = - max(beta);

              EEtmp = E(i,j,:,:,z);

              Rup (i,j,z) = S(i,j,z) + n + sum(EEtmp(:));
          end
      end
  end

A,R,S are [N x M x P] matrices.

I tried a lot by myself, but I have no confidence with the tricks useful to remove loops. Can anyone help me?

Matteo

Answer 1

[Sean de Wolski]

Just preallocating Rup should speed this up:

First line:

Rup = zeros(size(A));

Answer 2

[Matteo]

Thanks! how much will it affect the speed?

I'm also interested to learn something new about the for loops removal.

[Sean de Wolski]

Unless this is going into production or being run millions of times, the time it would take to "vectorize" this will take longer than the running time of the code. Preallocating will speed it up most of the way.

As for how much you will see for a speedup? Try it!

[Matteo]

I tried and the execution time was reduced by 20%, thank you!

Anyway i need to speed it up more, have you other advices?