title: Networkx: Differences between pagerank, pagerank_numpy, and pagerank_scipy?
body: <p>Does anyone know about the differences in accuracy between the three different pagerank functions in Networkx?</p>
  
  <p>I have a graph of 1000 nodes and 139732 edges, and the "plain" <code>pagerank</code> function didn't seem to work at all -- all but two of the nodes had the same PG, so I'm assuming this function doesn't work quite as well for large graphs?</p>
  
  <p><code>pagerank_numpy</code>'s values also seemed to be a little bit more spread out than <code>pagerank_scipy</code>'s values. The documentation for this function says that "This will be the fastest and most accurate for small graphs." What is meant by "small" graphs?</p>
  
  <p>Also, why doesn't pagerank_numpy allow for <code>max_iter</code> and <code>tol</code> arguments?</p>