# Computational neuroscience - I have a 116x116x226 I need to calculate the eigenvalues for this array can anyone help me?

2 views (last 30 days)
Elizabeth Drybrugh on 20 Feb 2018
Edited: Andrei Bobrov on 20 Feb 2018
I have tried to use eig but doesn't work for 3D arrays. Any help will be greatly appreciated

Roger Stafford on 20 Feb 2018
Edited: Roger Stafford on 20 Feb 2018
A 3D array is not a matrix, and matrix multiplication is not defined for such arrays. Eigenvalues and eigenvectors are defined in terms of matrix multiplication, and therefore do not have a definition for 3D arrays.
You can, however, find eigenvalues and vectors for each of the 226 layers in your array since each one is a square matrix. That would make sense.
Andrei Bobrov on 20 Feb 2018

Andrei Bobrov on 20 Feb 2018
Edited: Andrei Bobrov on 20 Feb 2018
[m,n] = size(d);
ii = rem(0:n-1,m)+1 ~= 1;
nn = 1:n;
n1 = nn(ii);
n2 = repmat(1:m,1,ceil(n/m));
n2 = n2(nn);
n2 = n2(1:end-1);
n2 = n2(n2 ~= m);
out = d(sub2ind([m,n],n2,n1));
second variant
[m,n] = size(d);
m2 = m*m;
out = d((m+1:m+1:m2)' + (0 : ceil(n/m)-1)*m2);

### Categories

Find more on Linear Algebra 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!

Translated by