# Converting matirx into vektor inside a cell array

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Antonio Sarusic on 20 Feb 2020
Commented: Antonio Sarusic on 20 Feb 2020
Hello,
I have a cell array V (1024x1280 cells).
In every cell of this cell array I saved a 2x2 matrix.
Now i want to split this matrix into two column vectors and save these vectors in two cell arrays ev1 and ev2.
And all this for the entire cell array V.
for i=1:n
for j=1:m
[ev1{j,i}] = V{j,i}(1,1);
[ev2{j,i}] = V{j,i}(1,2);
end
end
But with this I only get single values.
Thanks,
Antonio

Alex Mcaulley on 20 Feb 2020
Try with this:
for i=1:n
for j=1:m
ev1{j,i} = V{j,i}(:,1);
ev2{j,i} = V{j,i}(:,2);
end
end
Antonio Sarusic on 20 Feb 2020
Thanks, this is working!

the cyclist on 20 Feb 2020
ev1 = cellfun(@(x)x(:,1),V,'UniformOutput',false);
ev2 = cellfun(@(x)x(:,2),V,'UniformOutput',false);
the cyclist on 20 Feb 2020
I will say this, though. It looks like you could use 4-dimensional arrays instead of cell arrays.
V = zeros(m,n,2,2);
D = zeros(m,n,2,2);
for i=1:n
for j=1:m
HesseM = [Gxx(j,i) Gxy(j,i); Gyx(j,i) Gyy(j,i)];
[V(j,i,:,:),D(j,i,:,:)] = eig(HesseM);
end
end
Then the next operation is ...
ev1 = V(:,:,:,1);
ev2 = V(:,:,:,2);
and other downstream operations might also be easier, and probably execute faster.
Antonio Sarusic on 20 Feb 2020
Ok. I'll give it a try.
Thank you!