Very long execution time for loop "end" command

MATLAB profile viewer showed me that over 20% of my run-time is spend on a loop "end" command. I understand that this line is called millions of times, but there are other lines inside that loop that take less time although they actually do something! Help please.

Answer 1

[Roger Stafford]

If NInj is a large number, the lines 70 and 71 are needlessly repetitive and therefore constitute a very inefficient code. If you have room for a temporary additional (NStg-1)-by-NInj matrix (D), the following code should be much faster:

   D = zeros(NStg-1,NInj);
   P = 2*NPrd+(j-1)*NInj;
   k = (1-X)/sqrt(2);
   for i = 1:NInj
     t = 0;
     for n = 2:NStg
       t = t*X+(I(n,i)+I(n-1,i))*k;
       D(n-1,i) = t;
     end
   end
   H(P+(1:NInj),P+(1:NInj)) = D.'*D;

[Ali Jamali]

You just blew my mind. Can you tell me what does .'* do?

[per isakson]

See transpose

[Ali Jamali]

I got it. Thanks very much!