Element-wise multiplication does not generate correct armadillo code!
Math statements:
Q^{2,2} A = [1,1;1,1];
Q^{2,2} B = [1,2;3,4];
Q^{2,2} C = A .* B;
produce wrong armadillo C++ code:
mat C = A .* B;
Armadillo uses % for element wise multiplication.