Error in igraph::distances(g) :

[brainiac-source]

Error in igraph::distances(g) :
At vendor/cigraph/src/paths/bellman_ford.c:162 : Negative loop in graph while calculating distances with Bellman-Ford algorithm. Negative loop detected while calculating shortest paths
I am getting this error for some brain plots, rest are working fine. I cannot understand what the issue is

[szhorvat]

This occurs when passing negative edge weights/lengths to shortest path functions, and there is a cycle around which the total length is negative. Shortest path calculation makes no sense in this case as paths could be made arbitrarily short by going around the cycle multiple times.

I will improve the error text in igraph to be more descriptive.