Summing output of for loop.

I have a for loop producing an n x m matrix E fr every time the for loop runs. But i then need to sum all the output matrices from the for loop. Can anyone suggest how to do this. -I dont need to save the individual matrices, just the sum of them. Thanks

[Jan]

What have you tried and which problem has occurred? Actually the procedure is trivial: Create the new matrix in each iteration and sum it up.

Answer 1

[Geoff]

I gather you have the following situation, or something similar.

nloops = 100;
sumE = zeros(n,m);

for i = 1:nloops

    % This loop generates a new E
    E = [];
    for j = 1:n*m
      % magic goes here
    end

    % Now you want to sum E
    sumE = sumE + E;

end

Well, the answer is contained above. =)

[Jan]

Instead of "E=[]" a proper pre-allocation is recommended: "E=zeros(n, m)".

[Dougie]

This all makes sense apart from the:

for j = 1:n*m

% magic goes here

end

is this just meant to be the calculation for E?

Thanks

[Geoff]

Yes, you stated that you already had a loop to compute E, so I slapped in a magical loop to compute E as a placeholder. And yes, as per Jan Simon's reminder, I would usually preallocate the array instead of declare it empty.

[Jan]

@Dougie: If you had posted the relevant part of your program, Geoff wouldn't has to guess the part for calculating E.

Beside the tiny detail of the pre-allocation, Geoff's solution seems to be optimal. +1

[Tilkesh]

Yes really it is magic