MATLAB Answers


how to sum matrics inside a cell array?

Asked by Kobi
on 6 Aug 2014
Latest activity Commented on by lingyun ding on 26 Nov 2017
Accepted Answer by dpb
i have 4 matrics inside a cell and i need to sum them all currenyly i use this:
the original R is a cell with 4 matrics


Sign in to comment.



3 Answers

Answer by dpb
on 6 Aug 2014
Edited by dpb
on 22 Apr 2017
 Accepted Answer

Oh, misunderstood the query...that's simply
S =
1.3771 0.5139
1.1590 0.7149
>> all(all(S==R{1}+R{2}))
ans =
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... :(
Instead use
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).


It's not working for me either, error:"too many input arguments"
on 22 Apr 2017 bad, had tested only for two cells; I was thinking w/o checking that plus was enabled to handle a variable number of arguments but it isn't...see ERRATUM above Answer--dpb
Is there other methods to solve this problem? This methods is less efficient then the for-loop

Sign in to comment.

Answer by Evan
on 6 Aug 2014
Edited by 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.).


Sign in to comment.

Answer by 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 =

  1 Comment

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

Sign in to comment.