GraphX Pagerank Implementation
<p>So I'm a little confused by the GraphX pagerank implementation.</p>

<p><a href="https://github.com/apache/spark/blob/feaa07802203b79f454454445c0a12a2784ccfeb/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala#L115-L160" rel="nofollow">https://github.com/apache/spark/blob/feaa07802203b79f454454445c0a12a2784ccfeb/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala#L115-L160</a></p>

<p>In particular, line #138, <a href="https://github.com/apache/spark/blob/feaa07802203b79f454454445c0a12a2784ccfeb/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala#L138" rel="nofollow">https://github.com/apache/spark/blob/feaa07802203b79f454454445c0a12a2784ccfeb/graphx/src/main/scala/org/apache/spark/graphx/lib/PageRank.scala#L138</a>.</p>

<p>Why isn't page rank for a vertex defined as 
<code>
resetProb + (1.0 - resetProb) * msgSum
</code>
instead of
<code>
oldPR + (1.0 - resetProb) * msgSum
</code></p>

<p>Can anyone explain this difference? The links also don't point to master, sorry if anyone is confused by that, however, master still has the same code.</p>