PagerankDelta correctness

[chris1274]

It looks like you are discarding the residuals of all vertices every round, as opposed to only resetting residuals that are greater than the activation threshold. As a consequence, a vertex that takes more than one round to accumulate enough residual error to become active again, stays inactive, and the algorithm converges in less iterations than it should.

Maybe something like:

struct PR_Vertex_Reset {
  double* nghSum;
  PR_Vertex_Reset(double* _nghSum) :
    nghSum(_nghSum) {}
  inline bool operator () (uintE i) {
    if (nghSum[i] > epsilon2) nghSum[i] = 0.0; //reset only if we crossed threshold
    return 1;
  }
};

Please let me know if I am misunderstanding something here.