If you have prior probabilities then set prior.prob to these.
Otherwise prior.prob=NULL is the default i.e. use the sample
proportions as estimates of the prior probabilities. For d > 1, the kernel density estimate is computed exactly i.e. binning
is not used. For d = 1, the binned estimator from the
KernSmooth library is used.
For d = 1, 2, 3, if eval.points is not specified, then the
density estimate is automatically computed over a grid whose
resolution is controlled by gridsize (default is 101, 51 x 51
and 51 x 51 x 51 respectively).
For d > 3, eval.points must be specified.