Elliptic flow of muons from heavy-flavour hadron decays as a function of the collision centrality in $2.5 < y < 4$ and $3 < p_{\rm T} < 10$ GeV/$c$,in Pb-Pb collisions at $\sqrt {s_{\rm NN}}$ = 2.76 TeV. The results are obtained with scalar product and two-particle $Q$ cumulants Vertical bars (open boxes) represent the statistical(systematic) uncertainty, the horizontal error bars correspond to the width of the centrality bin. For visibility, the points from scalar product are shifted horizontally and the horizontal error bars are not plotted | |