How to add an unknown amount of number in matlab?

Question

Gennie 2014-10-20

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编辑： Image Analyst 2014-10-22

I am creating a code to get the resultant of an unknown number of vectors by addition. I can't think of a way to add unknown amount of numbers in a loop. Here's my code so far. It only adds two numbers in that kind of equation.

for n=2:1:sv(2)
    xx=vect{1,n-1}(1)+vect{1,n}(1)
end

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Answer 1

David Sanchez 2014-10-20

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Not sure about your intentions, i created a dummy cell and a solution for what i think is your problem:

vect=cell(5,3);% initialization of dummy cell
for r=1:5
    for c=1:3
        vect{r,c} = rand(3,1); % random 3x1 array in each cell
    end
end
%%%the sumation
xx = 0; % initialize summation
for n=1:length(vect(1,:)) % for-loop from first to last (unknown) element
    xx = xx + vect{1,n}(1); % iterate along the column
end

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Answer 2

David Young 2014-10-20

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The trick is to add on to the result vector each time through the loop.

I don't understand what sv is in your code, and I'm not sure why you select the first element of each vector, so here's a simpler example which adds up all the vectors stored as elements of a cell array, assuming they are all the same size:

% example data
vect = {[1 2 3] [4 5 6] [7 8 9]};   % can have any number of elements
sumVec = 0;
for ii = 1:numel(vect)
  sumVec = sumVec + vect{ii};
end

If your initial vectors are stored as the rows or columns of a matrix, it's even simpler - just a single call to the sum() function.