r - calculating alpha & power centralities by igraph -

i calculating alpha , power centralities graph igraph package got error

alpha.cent<-alpha_centrality(graph,loops = f)     error in .local(a, b, ...) :        cs_lu(a) failed: near-singular (or out of memory) pow.cent<-power_centrality(graph,loops = f) error in .local(a, b, ...) :        cs_lu(a) failed: near-singular (or out of memory) 

does know mean? , can fix it?

i not sure whether solves exact problem did not provide sample data, had same problem , solved playing around option exponent = [...]. igraph vignette suggest try values ranging -1 1 in 0.1 steps.

these 2 websites/papers discuss beta value of power centrality (which exponent in igraph formula) in bit more detail:

https://www.cmu.edu/joss/content/articles/volume12/rodan.pdf http://www.faculty.ucr.edu/~hanneman/nettext/c10_centrality.html

edit

another potential source errors isolated vertices. check whether have such , delete them can following:

sum(degree(g) < 1) # if value non-zero have isolates gg <- delete_vertices(g, which(degree(g) < 1))