Very long execution time for loop "end" command

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Ali Jamali
Ali Jamali 2015-3-12
评论： Ali Jamali 2015-3-12
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.

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Roger Stafford
Roger Stafford 2015-3-12
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;

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