This PR implements a HistogramPdf class derived from the Source class and parent to the DensityEstimatingSource class. It is useful for Sources that get their PDF values from a histogram (stored as multihist Histdd object) instead of some other (analytical/numerical/continuous) function which may be expensive to compute.
Secondly this class is used by DensityEstimatingSource to store its events and do density estimation.
This PR implements a HistogramPdf class derived from the Source class and parent to the DensityEstimatingSource class. It is useful for Sources that get their PDF values from a histogram (stored as multihist Histdd object) instead of some other (analytical/numerical/continuous) function which may be expensive to compute. Secondly this class is used by DensityEstimatingSource to store its events and do density estimation.