Hi, I ran into trouble using arpack with non-symmetric matrices. E.g.
A <- matrix(runif(16,-1,1),4) fct <- function(x,extra=NULL)A %*% x arpack(fct, options=list(n=ncol(A), nev=1, ncv=3), sym=FALSE)
generaly outputs eigenvectors that don't solve the aigenvalue equation Av=lv, where l seems to correspond to the results obtained with eigen(). Is a full testing of arpack() planned in a near future?
Anyway, igraph is just a great piece of software! Bravo!