Calculate the summation of matrices within a cell

Hello

I know this is an easy question but I am a bit stuck

I have generate a set of data which I am storing into structures. Then I calculate a quantity over them. My problem is two parted, first i tried to save them into a new structure but it did not allow me, so I stored them into a cell array (which worked perfectly)

In the next loop want to calculate the summation of the available matrices inside the array for a given {n}

field_names = fields(HsD1); %structure field_names2 = fields(TpD1); %structure

for n=1:11%size(field_names2)
    pause(0.01)
    P=([])
    fn2=char(field_names2{n})
    fn =char(field_names{n})
%     contourf((((TpD1.(fn2).*(HsD1.(fn).^2))./1000)),colorbar %check visually if it works
    P=((((TpD1.(fn2).*(HsD1.(fn).^2))./1000));
    Pow(n)=P

% Pow=([])
% Pow(n)=P % This does not work
%    
end

then the addition should be

for i=1:11

      Average=[]
      Average{n} = sum(Pow{n})/11

end

The matrices are 200x200 and I would like to add all together (matricewise), each point represent a different day. That is why all the point in all the matrices have to added and averaged.

How is this possible to be done? I also tried the cell2str command to convert my cell array into structure but no luck, I would prefer if I could save Pow in a structure from the start

thank you