PL1 computes and plots the Rank-Exponent Power-Law in FFF99.  This power-law states that the
outdegree , dv, of a node v, is proportiaon to the rank of the node, rv, to the power of a constant,
R.  (Requires Gnuplot to plot and Ghostview to view plot)

Contributors:   Michalis Faloutsos, Petros Faloutsos, Christos Faloutsos
Reference:      [FFF99] On Power-Law Relationships of the Internet Topology, in ACM Sigcomm 1999.   
Implemented by: BRITE Development Team
