[igraph] Vertex numbering from zero?

[Matthew Walker]

Hi,

I hope this is a very simple newbie question!  Can you please confirm 
that vertex numbering starts with zero (for the C-library version of 
iGraph, as is discussed in the introduction of the reference manual 
[1])?  I ask this because I just read the documentation on 
igraph_subgraph() [2] which seems to indicate that numbering starts with 
one.

[1] http://igraph.sourceforge.net/doc/html/ch04s01.html
[2] http://igraph.sourceforge.net/doc/html/igraph_subgraph.html

Thanks!

Matthew