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How can we reduce the execution time of this whole code?

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Sadiq Akbar
Sadiq Akbar 2023 年 2 月 8 日
コメント済み: Sadiq Akbar 2023 年 2 月 8 日
I want to minimize the "execution time" of the code given in the attachment. You can run the m file "main".
  2 件のコメント
Dyuman Joshi
Dyuman Joshi 2023 年 2 月 8 日
In myfunction, Why are you pre-allocating an empty matrix?
K = length(u); %Constant4
c=zeros(M*N, length(u)-K);
ce=zeros(M*N, length(u)-K);
%Modify it as
c=zeros(M*N,K);
ce=zeros(M*N,K);
And club the two for loop together -
for g= 1:K
c(:,g)=kron(a(:,g),f(:,g));
end
for g= 1:K
ce(:,g)=kron(ae(:,g),fe(:,g));
end
into
for g = i %i is already defined in the code
c(:,g)=kron(a(:,g),f(:,g));
ce(:,g)=kron(ae(:,g),fe(:,g));
end
Additionally, pre-allocate Sol and Fitness in fp1
After these changes, the code runs in 2.5674 secs in i3-5th gen, 8gb RAM, which imo is fast enough.
Sadiq Akbar
Sadiq Akbar 2023 年 2 月 8 日
Thanks a lot dear Dyuman Joshi for your kind response. In myfunction, the pre-allocation of an empty matrix speeds upt the process? With this its time is reduced and without this, it take more time. Yes, you are right, the two for-loop can br clubbed togather. But how to pre-allocate Sol and Fitness in fp1?

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Dyuman Joshi
Dyuman Joshi 2023 年 2 月 8 日
I am aware that pre-allocation speeds up the process, but pre-allocating an empty matrix doesn't reserve any memory for the operation and it is slower than pre-allocating with a zeros matrix. See below -
Modify the pre-allocation as I have suggested above.
v=1e6;
y=zeros(v,0);
z=zeros(v,1);
whos y z
Name Size Bytes Class Attributes y 1000000x0 0 double z 1000000x1 8000000 double
tic
for ix=1:v
y(ix)=i;
end
toc
Elapsed time is 0.151647 seconds.
tic
for ix=1:v
z(ix)=i;
end
toc
Elapsed time is 0.025546 seconds.
"But how to pre-allocate Sol and Fitness in fp1?"
It's clear from the code
%for i=1:psize
% Sol(i,:)=Lb+(Ub-Lb).*rand(1,d);
% Fitness(i)=fun(Sol(i,:));%--------------------(1)
%end
Fitness has psize elements, so size is (1xpsize, as the output of the function myfunction is a scalar value)
and Sol has psize rows and d columns.
Pre-allocate zero matrices accordingly.
  3 件のコメント
Dyuman Joshi
Dyuman Joshi 2023 年 2 月 8 日
"I found that the time with pre-allocation is lower than without pre-allocation."
I am well aware of this. But that was not my point.
Nevertheless, what you have done now is better than what you did before.
How did you arrive at n+1 and N_iter?
Ugh. I specifically mentioned what to use for pre-allocation of Sol and Fitness -
"Fitness has psize elements, so size is (1xpsize, as the output of the function myfunction is a scalar value)
and Sol has psize rows and d columns.
Pre-allocate zero matrices accordingly. "
Use this -
Sol=zeros(psize,dim);
Fitness=zeros(psize,1);
Sadiq Akbar
Sadiq Akbar 2023 年 2 月 8 日
Thanks a lot dear Dyuman Joshi for your kind response. Indeed now it works. But still the time is not reduced so much. Can you convert the for-loops inside fpa1 to vectorized form because this may redue the time?

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