  We have argued that the azimuthal symmetry and asymmetry components in
fourier expansion of particle momentum azimuthal distribution, $v_n$ (n=0, 1,
2, ...), should be calculated as an average of $cos(n\phi)$ first over
particles in an event and then over events (event-wise average) rather than "an
average over all particles in all events" (particle-wise average). In case of
large centrality (multiplicity) bin the particle-wise average is not accurate
because the influence (fluctuation) of particle multiplicity was not taken into
account.
