[Xy-pic] "Dimension too large" (was: question regarding xy-pic)

[Frank Drewes]

Hi again!

For your information: I finally discovered that the problem vanishes  
if I remove the authors' package inclusion comman \usepackage 
{lmodern}. In other words, there must be some strange kind of  
incompatibility between lmodern and xy-pic, at least on my system  
(Mac OS X, gwTeX distribution based on TeX Live). If someone could  
explain the deeper reason (so that I need not remove the lmodern from  
the authors' sources), I would be grateful for a short message.

Regards,
Frank