Meant to encapsulate information representing a Quadrilateral which is
going to be rendered on a VisAD display without being
subject to the usual VisAD transformations.
The following class represents a quantity -- usually a physical one
such as energy, viscosity, or velocity (although an artificial one
such as "money" should be possible).
QuickSort sorts a set of samples in R using a quicksort
algorithm combined with an insertion sort algorithm to
avoid an excess number of recursive calls.