Re: [igraph] arpack - unkown ARPACK option(s): sym

[Gábor Csárdi]

'sym' is an argument to ARPACK, not an option to put in the arpack options list:

...

baev <- arpack (f2, options=list (n=vcount (g), nev=3, ncv=8, which="LM", maxiter=200), sym = TRUE

...

The example was wrong before, it is correct now:

http://igraph.org/r/doc/arpack.html

Gabor

On Sun, Feb 23, 2014 at 7:19 AM, Hermann Norpois <address@hidden> wrote:

Hello,
I tried the example of arpack{igraph} and I did not make it run with the option sym=TRUE


g <- erdos.renyi.game (1000, 5/1000)
M <- get.adjacency (g, sparse=TRUE)
f2 <- function (x, extra = NULL){cat ("."); as.vector (M %*% x)}
 baev <- arpack (f2, options=list (n=vcount (g), nev=3, ncv=8, sym = TRUE, which="LM", maxiter=200)) # like in the example
Fehler in arpack(f2, options = list(n = vcount(g), nev = 3, ncv = 8, sym = TRUE,  :
  unkown ARPACK option(s): sym

Without the option sym=TRUE it works but I get a complex vector:
 baev <- arpack (f2, options=list (n=vcount (g), nev=3, ncv=8, which="LM", maxiter=200))
.............................................................................................................................................................................................................>
 baev$vectors[,1][1:3]
[1] 0.04375092+0i 0.01087742+0i 0.01028816+0i

complex=FALSE does not work either:
 baev <- arpack (f2, options=list (n=vcount (g), nev=3, ncv=8, which="LM", maxiter=200, complex=FALSE))
Fehler in arpack(f2, options = list(n = vcount(g), nev = 3, ncv = 8, which = "LM",  :
  unkown ARPACK option(s): complexM <- get.adjacency (g, sparse=TRUE)

Can you please give me an hint.

Thanks

Hermann

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