Re: [igraph] Strange pagerank values

[Tamás Nepusz]

I'm not sure what is happening here, but apparently the problem is resolved if 
we start the PageRank calculation from a completely uniform initial vector 
instead of the in-degree vector plus some random noise. The problem is that it 
breaks some of our PageRank test cases where the in-degree vector plus some 
random noise seemed to work better.

T>

On 19 Mar 2013, at 15:28, Tamás Nepusz <address@hidden> wrote:

> Hi,
> 
> You are right, the PageRank values should all be between 0 and 1. Your graph 
> seems to be a corner case for which the ARPACK solver fail to converge, 
> although I have no idea why. I will evaluate and get back to you.
> 
> -- 
> T.
> 
> On 19 Mar 2013, at 01:22, Krishna Sandeep Reddy Dubba <address@hidden> wrote:
> 
>> Hi all,
>> I am trying to compute pagerank for a graph and I am getting strange values 
>> for pagerank. to my knowledge, the page rank values should be between 0 and 
>> 1 but i get very large or very small number (> 1 and < 0). I attach the .gml 
>> file and here is the output. Please let me know what I am doing wrong or is 
>> this graph some strange special case?
>> 
>> In [4]: import igraph
>> In [5]: g = igraph.read(f)
>> In [6]: pr = g.pagerank()
>> In [7]: pr
>> Out[7]: 
>> [1323658113126271.8,
>> -264731622625256.4,
>> -264731622625256.44,
>> -264731622625256.44,
>> 264731622625252.84,
>> -264731622625256.4,
>> 264731622625252.94,
>> -264731622625256.44,
>> -264731622625254.56,
>> 264731622625252.78,
>> -1588389735751520.0,
>> 4500437584629358.5,
>> -264731622625254.47,
>> -264731622625254.53,
>> -264731622625254.5,
>> 264731622625252.8,
>> -264731622625256.4,
>> -264731622625256.47,
>> -529463245250509.7,
>> 264731622625253.78,
>> -264731622625256.34,
>> -264731622625256.34,
>> -264731622625256.4,
>> -264731622625256.44,
>> -264731622625256.47,
>> -264731622625256.4,
>> -264731622625256.44,
>> -264731622625256.44]
>> 
>> Thanks,
>> dksr
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>