CUDA 8 SSSP Tip:: When nvgraphSssp (part of the nvGraph library, new for CUDA 8) returns the “Not Converged” status, you *can* still call nvgraphGetVertexData to find the negative weight cycle(s) by examining costs and looking at which vertices have spiraling down in cost.

(Yes, nvgraphSssp works correctly in graphs with edges with negative weights, but no negative weight cycles.)