Tamas, thanks for your reply. the calculation just died: Error in page.rank(graph) : At arpack.c:1178 : ARPACK error, The Schur form computed by LAPACK routine dlahqr could not be reordered by LAPACK routine dtrsen. Timing stopped at: 127517.2 3.297 127803.5
I tried page.rank(graph, options=list(niter=2)) and it is still running: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 36756 sam 20 0 13.8g 13g 4564 R 99.6 43.5 1131:50 /usr/lib64/R/bin/exec/R --no-save --no-restore -q the help page for arpack which describes options for page.rank does not mention epsilon. On Wed, Jul 31, 2013 at 4:23 PM, Tamás Nepusz <[email protected]> wrote: >> page.rank has been running forever: > [...] >> on >> >> IGRAPH DN-- 12062801 15279166 -- >> attr: name (v/c) >> >> is this normal? > Not sure but I wouldn't rule it out -- your graph is pretty large and ARPACK > can be a tad bit slow. I have just tried it on an Erdos-Renyi graph of > similar size and it also did not terminate for a while. On the other hand, > you might be experiencing a convergence issue with ARPACK. Sometimes it > happens that ARPACK fails to detect convergence (at least within the machine > epsilon) and performs the maximum number of allowed iterations with > essentially no improvement after the first few iterations -- then it bails > out with a warning saying that the maximum number of iterations has been > reached. Try increasing the epsilon value a bit when invoking page.rank() to > see if it terminates faster or not. Or decrease the maximum number of > iterations allowed. I'm not familiar with the R interface but I think there > is an options=... argument to page.rank where you can specify some options > that ARPACK will use. > > An alternative solution if you are feeling adventurous and you don't mind > compiling igraph from source: try the 0.7-prpack branch of igraph > (downloadable from Github): > > https://github.com/igraph/igraph/tree/0.7-prpack > > This branch uses the excellent PRPACK package instead of ARPACK to calculate > PageRank scores. PRPACK does all sorts of neat tricks to ensure faster > convergence for PageRank calculations. The branch will be merged with the 0.7 > development tree sooner or later but it still needs more testing. > > All the best, > Tamas -- Sam Steingold <http://sds.podval.org> <http://www.childpsy.net/> _______________________________________________ igraph-help mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/igraph-help
