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How can I measure time on MATLAB?

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Omar B.
Omar B. on 24 Jul 2020
Commented: Omar B. on 25 Jul 2020
Hi, I am trying to measure the running time of solving system of linear equations using tic , toc. I have to compute the system of linear equation with (A+aI) for different scaler a in one code. How to measure the time of computing the system of linear equations for all a. Do we need to compute the total as I did below or we need to take the average of time?
n=200;
A=full(gallery('tridiag',n,1,2,1));
b=randn(n,1);
tic
[L,U]=lu(A+3*eye(n));
t=L\b;
x=U\t;
time(1)=toc;
tic
[L1,U1]=lu(A+6*eye(n));
t1=L1\b;
x1=U1\t1;
time(2)=toc;
total=time(1)+time(2);

Answers (1)

David Hill
David Hill on 24 Jul 2020
n=200;
A=full(gallery('tridiag',n,1,2,1));
a=[3,6];
b=randn(n,1);
for k=1:length(a)
tic
[L,U]=lu(A+a(k)*eye(n));
t(k)=L\b;
x(k)=U\t(k);
time(k)=toc;
end
totalTime=sum(time);
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