Question

I have following function which I would like to apply to each element:

function result = f(a, b, bs)
    % Simplified code
    result = a
    for i=0:bs
        result = dosomething(result, b(i))
    end
end

% Use
arrayfun(@result, gpuArray(A), gpuArray(B), size(B));

Is there a way of ‘tricking’ MATLAB into thinking b is scalar for purpose of passing to function?

Answer 1

The only way to do it is to use bsxfun function:

C = bsxfun(f, A, B') % A is column vector

is more or less equivalent to

C(i,j) = f(A(i,1), B(j,1))

Other useful function is repmat.

Then the series of matrices and vectors are JITted so there is in effect no O(MN) space penalty (checked by nvidia-smi).