# how to sum matrics inside a cell array?

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Kobi on 6 Aug 2014
Commented: LD on 26 Nov 2017
i have 4 matrics inside a cell and i need to sum them all currenyly i use this:
R=R{1}+R{2}+R{3}+R{4}
the original R is a cell with 4 matrics

dpb on 6 Aug 2014
Edited: dpb on 22 Apr 2017
Oh, misunderstood the query...that's simply
S=plus(R{:})
S =
1.3771 0.5139
1.1590 0.7149
>> all(all(S==R{1}+R{2}))
ans =
1
>>
Just used two cells here, but works for any number. As noted elsewhere sizes must be commensurate.
ERRATUM Does NOT work as written for any number of cells; plus isn't as smart as I was thinking it was/is... :(
S=sum(cat(3,R{:}),3);
As another poster noted, all cells must contain conformantly-sized arrays.
NB: The result will be class of the content of the cell (default double, of course).
LD on 26 Nov 2017
Is there other methods to solve this problem? This methods is less efficient then the for-loop

Evan on 6 Aug 2014
Edited: Evan on 6 Aug 2014
Are all the matrices in your cell array the same size? If so, this should work:
% Get random cell array with n cells. Here n = 3
A = {rand(4) rand(4) rand(4)}
n = size(A,2);
% Get size of matrices in cell.
matSize = size(A{1},1);
B = reshape(cell2mat(A),matSize,[],n);
% Sum 3D matrix along 3rd dimension
C = sum(B,3);
If they're different sizes, this either wont work or we need more information about how you want the different sizes handles (e.g. trimming, padding, etc.).

dpb on 6 Aug 2014
One way, seems should be better but it's still first cup o' coffee this morning...
>> R={rand(2) rand(3)}
R =
[2x2 double] [3x3 double]
>> sum(cellfun(@(x) sum(x(:)),R))
ans =
8.7056
>>
Kobi on 6 Aug 2014
this is not what i need i need to + sum the matrics like this A=rand(7)+rand(7)+rand(7)+.... and to recive one matrix each and every element in one matrix is added to another corresponding element the only problem is that all of the matrics are inside a cell

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