matlab - Im looking for a way to add up elements of two arrays

Question

i am looking for a way that i can add up elements in an array such that the first element of the first array is added to every element in the second array, then the second element in the first array is added to all every element in the second array and so on. The final vector will be length(a)*length(b) long

for example...

a=[1,2,3,4] b=[5,6,7] answer = [(1+5),(1+6),(1+7),(2+5),(2+6),(2+7),(3+5),(3+6),(3+7),(4+5),(4+6),(4+7)] =[6,7,8,7,8,9,8,9,10,9,10,11]

Answer 1

Read up on bsxfun. It's very useful for this kind of things (and usually faster than arrayfun or for loops):

result = bsxfun(@plus, a(:).', b(:)); %'// matrix of size numel(b) x numel(a)
result = result(:).'; %'// linearize to a vector

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Or, a little more freak: kron does what you want with products instead of sums. So:

result = log(kron(exp(a),exp(b)));