Examples of the fit to the D-meson average azimuthal-correlation function, for $5 < \ptD < 8$~\GeVc, $\ptass > 0.3$~\GeVc in pp collisions (left), and for $8 < \ptD < 16$~\GeVc, $1 < \ptass < 2$~\GeVc in \pPb collisions (right). The statistical uncertainties are shown as vertical error bars. The fit function described in Eq.~\ref{equ:Fit} is shown as a red solid curve. Its different terms are shown separately: near-side generalised Gaussian function, away-side Gaussian function, and baseline constant term. The scale uncertainty (see Sec.~\ref{sec:Systematics}) is also reported for completeness.