> I am wondering why the dates command in chron package does not work 
> in the following situation: 
> 
> cut(dates(c(23,45,67),origin=c(1,1,2004)),"months") 

It seems there are problems not only with cut.dates but also with cut.POSIXt.   For example,

   z <- seq(ISOdate(1900,1,1),by="day",length=100)
   b <- z[format(z,"%d")=="09"]    # break points on 9th day of month
   cut(z,b)

gives the error message:

   Error in sort(breaks) : `x' must be atomic


