[R] using minor tickmarks with xYplot

[Viet Nguyen]

Hi all,

I'm trying to make a plot with the function xYplot from package Hmisc in 
R.  I would like to have minor tick-marks on the axis.  This should be a 
common simple feature to have but I don't seem to find any discussion on 
the topic.

Following is one of the things I tried and the error returned:

xYplot(y~x,data.frame(x=seq(1,10),y=runif(10)),minor.ticks=c(3.5,5.5))
Error in panel(x = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), y = 
c(0.88172451662831,  :
    object "gfun" not found

It's important that I use "xYplot" and not "plot" so function 
minor.tick() is not useful.

Anything I can try?  Thanks in advance for your help.

vn