  A finite-dimensional matrix representation of the Jackson $q$-differential
operator $D_q$, defined by $D_qf(x)$ $=$ $(f(qx)-f(x))/(x(q-1))$, is written
down following Calogero. Such a representation of $D_q$ should have
applications in $q$-analysis leading to the corresponding extensions of the
numerous results of Calogero's work.
