
From:  Martin Tomko 
Subject:  Re: [igraph] errors using power.law.fit 
Date:  16 Nov 2010 11:41:30 +0100 
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Hi guys,yes, that is my reading of the paper too. NOw, what is the relation of the BFGS method suggested by Gabor and the method they use? Can I apply it?
I do indeed have discrete data (as anyone working with graph degree distributions would) and I understand that there is no single perfect power law adistribution I could fit to it, but I need an approximation. The alpha parameter and possibly an estimate of the goodness of fit (btw, I am accessing the result of the power law fiting as follows:
fitdegS4<power.law.fit(degrees,method="BFGS") alpha< coef(fitdegS4)[[1]])is there any simpler method to get the alpha and if possible the parameters? I am still not sure how best to access S4 objects, seems like you need a method, and I only found coef for a mle class object, but nothing for the goodness of fit parameter which actually gets displayed if I only list fitdegS4....
Thanks Martin On 11/16/2010 11:28 AM, Tamas Nepusz wrote:
Which is quite surprising, because there is no exact formula for discrete data AFAIK.Correction: no, they don't calculate alpha directly, they just simply try every possible alpha with some granularity in a given range, calculate the likelihood, and then choose the alpha which yields the maximal likelihood.
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