Multiplying each cell in an array by a column vector

I have this code:

p_m = ones(m,N) .* 1/m;
for i = 1:N
    temp{i} = cellfun(@(x,y) x.*y, p_m(:,i),energy_self{i}(:), 'UniformOutput',false);
end
self_energy = sum(sum([temp{:}]))

where energy_self is a 1xN cell array with each cell having a mxm matrix. I want to multiply cell 1 by the first column of p_m, cell 2 by the second column, etc. Then when that's done, add all the elements of the cell array into one number.

Any ideas?

Thanks in advance.

Answer 1

[Rik]

You should use a loop. That makes it a lot easier to write the indexing you need, and it will be faster.

Matrix operations are the fastest in Matlab, followed by loops, followed by loops obfuscated by cellfun or arrayfun. One exception: the legacy syntax of cellfun (e.g. cellfun('isempty',C)) can be faster than a loop.

[Stacy Genovese]

Thanks. Got it working

[Stacy Genovese]

This is what i did:

 for residue = 1:N
        temp{residue} = p_m(:,residue) .* energy_self{residue};
 end
 self_energy = sum(sum([temp{:}]));

Thanks so much!

[Rik]

You're welcome. If I solved your issue, please consider marking it as accepted answer. That will help future users find a solution more quickly.

You could also consider doing the sumation inside the loop already:

self_energy=0; 
for residue = 1:N
    temp = p_m(:,residue) .* energy_self{residue};
    self_energy = self_energy + sum(temp(:));
end