For Loop in 3D Array

17 views (last 30 days)
MarshallSc
MarshallSc on 31 May 2022
Commented: MarshallSc on 31 May 2022
For 2D arrays, the operation that I want to execute is:
a = rand(3,3);
for i = 1:numel(a)
for j = 1:numel(a)
out(i,j) = (a(i) - a(j)) / (a(i) + a(j));
end
end
Which will turn the out into a skew-symmetric matrix. Now I want to perform the same operation instead the matrix is in 3D, how can I do that? The speed is important since my original matrix is (100,100,726). Thanks!

Accepted Answer

Dyuman Joshi
Dyuman Joshi on 31 May 2022
Edited: Dyuman Joshi on 31 May 2022
a = rand(3,3,4);
for k=1:size(a,3)
y=a(:,:,k);
for i=1:size(y,1)
for j=1:size(y,2)
out(i,j,k)=(y(i) - y(j))/(y(i) + y(j));
end
end
end
out
out =
out(:,:,1) = 0 0.6498 -0.1418 -0.6498 0 -0.7248 0.1418 0.7248 0 out(:,:,2) = 0 -0.6166 -0.5396 0.6166 0 0.1154 0.5396 -0.1154 0 out(:,:,3) = 0 0.1018 0.1400 -0.1018 0 0.0387 -0.1400 -0.0387 0 out(:,:,4) = 0 0.2123 0.1857 -0.2123 0 -0.0277 -0.1857 0.0277 0
  2 Comments
Dyuman Joshi
Dyuman Joshi on 31 May 2022
It will be skew-symmetric matrix. I have made an edit, take a look at it again.
MarshallSc
MarshallSc on 31 May 2022
Thanks, yeah, changing the i and j indices from 1:size(y,1) to numel(y) would do the trick. Thanks again!

Sign in to comment.

More Answers (0)

Categories

Find more on Get Started with MATLAB in Help Center and File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!