Speeding up nested for-loop

Hi

I have the following nested for-loop, containing some if-statements. It is running horribly slow, so I would be very happy to get some hints and tricks to speed it up. Can I vectorize it somehow? Or use parallel computing?

for xi= 1:N
    for yi= 1:N

          a  = A(:,xi,yi);   %a is a vector
          b  = B(:,xi,yi);   %b is a vector
          D  = a-b;

          if( max(D./a)<1e-3 )
              test_var=2.0;  
          else

              F_min = F(a, b, 0); %F is a script I wrote
              F_max = F(a, b, 1); %F is a script I wrote

              if( F_min*F_max>0.0 )
                  test_var=2.0;
              else
                  test_var = F(a, b, 2);
              end
          end

          var(1, xi,yi) = test_var;
      end
  end

[Star Strider]

It might help if you describe what you want to do in your code, the sizes of ‘A’ and ‘B’ (although they are likely equal), and listed ‘F’ and describe what it does.