Matrix power vs for loop
3 次查看(过去 30 天)
显示 更早的评论
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 个评论
采纳的回答
Angelo Yeo
2023-6-26
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 个评论
更多回答(1 个)
James Tursa
2023-6-26
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 个评论
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Quadratic Programming and Cone Programming 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!