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Can I somehow optimize this formula? I evaluate it many times and it takes much time…
w – 1xN double
phis – NxN double
x – Nx2 double
sum(w(ones([size(x, 1) 1]),:) .* phis, 2)
You’re taking the scalar product of each row of
phiswithw. You can do this easily using linear algebra.This matrix multiplication saves you calls to
sum,ones, andsize, which should make your code a lot faster. Furthermore, linear algebra operations are often very fast in Matlab, since that’s what the program is historically optimized for.