Matrix power vs for loop
3 views (last 30 days)
Show older comments
Hi.
I have to iterate a linear system of the type x(k+1) = Ax(k), with x being a vector of 1024 elements. I only care about the last vector obtained, this is, x(endtime).
What would be faster?
x0 =rand(1024,1)
x = x0;
for i = 1:endtime
x = A*x
end
or
x = (A^endtime) * x0
Thanks.
0 Comments
Accepted Answer
Angelo Yeo
on 26 Jun 2023
Hi Luisa,
If you only want to calculate the time it took to run a snippet of code, you can use tic and toc. Below is an example. You can see the latter one is faster.
endtime = 10000;
A = rand(1024, 1024);
case1 = tic;
x0 =rand(1024,1);
x = x0;
for i = 1:endtime
x = A*x;
end
toc(case1)
case2 = tic;
x = (A^endtime) * x0;
toc(case2)
0 Comments
More Answers (1)
James Tursa
on 26 Jun 2023
Note that the A^endtime method is probably going to be more accurate as endtime gets larger. The loop method can have a tendancy to build up errors.
0 Comments
See Also
Categories
Find more on Quadratic Programming and Cone Programming in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!