Re: [igraph] Question about finding power in a scale-free graph

[Narges Zarabi]

Dear Tamas,

Thanks for your answer. Do you have any idea of how the value of alpha will change by changing the power argument? Is there a mathematical formula which defines the relationship?

Regards, Narsis

On Sun, Feb 13, 2011 at 1:21 PM, Tamás Nepusz <address@hidden> wrote:

> I get an alpha = 2.8 , which is different from the power I used in building the graph. Does anyone have any explanation for this?

The power argument does not specify the alpha exponent of the degree distribution; it specifies the exponent used when igraph determines the attachment probabilities after a new vertex is added. power=1 corresponds to linear preferential attachment, which should indeed correspond to alpha = 3 in the infinite limit, so the value of 2.8 you get seems to be correct.

--
Tamas


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