how to write a function that multiplies any 2 matrices that are of compatible size by using nested for loop?

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Natalia Wong 2015-11-27

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回答： Bjorn Gustavsson 2015-11-27

For example not just a (2X2)matrix, but also for a (3X1) matrix and (3X3) matrix. I'm confused by a nested loop ? How do you nest it anyway? Thanks I am new to matlab

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Answer 1

Bjorn Gustavsson 2015-11-27

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You simply do something along these lines:

for i1 = 1:size(M1,1)
  for i2 = 1:size(M2,2),
    Res(i1,i2) = M1(i1,i2) + M2(i1,i2); % Or whatever operator you're interested in
  end
end

Above I've not bothered checking that this is the proper ordering of the indexing for your desired multiplication of matrices - since the * operator in matlab is intended to do matrix multiplication for you, I guess this is for the learning experience...

You should also pre-allocate the Res array (Res = zeros(sy,sx);) to avoid growing it incrementally which wastes lot of time.

HTH