[igraph] potential revamp of power.law.fit implementation

[Bob Pap]

Dear Gabor and Tamás,

You may want to consider upgrading the power.law.fit function in igraph to profit from developments documented in 

A. Clauset, C.R. Shalizi, and M.E.J. Newman, "Power-law distributions in empirical data" SIAM Review 51(4), 661-703 (2009). (arXiv:0706.1062, doi:10.1137/070710111)

which allow in-function assessment of the minimal degree value for the estimation of alpha.  As documented in the article, an implementation is available - also for R - in http://www.santafe.edu/~aaronc/powerlaws/ (function plfit.r). The results seem in line with the current igraph implementation for the graph I am working on with the added advantage of having the minimum degree estimated automatically!

Kind regards,

Bob