function in order to plot the same graph to postscript an d pdf

From: Ronny Klein

The myplot is something like this:

plot(x)
text(foo)

Aha, I was surprised that this worked for one of the two plots.
You could pass myplot as an expression, e.g. myplot =
expression(plot(x)), and then eval() that in the body of 

plot.both().

I've followed your advice and changed my function to 
something like this:

plot.both <- function{myplot, filename}{
     MYPLOT <- expression(myplot)
     pdf(file=paste(filename, ".pdf", sep=""))
     eval(myplot)
     dev.off()
     postscript(file=paste(filename, ".eps", sep=""))
     eval(myplot)
    dev.off()
 }

However the result is the same: the first one is actually 
printed but the 
second plot is empty. 

Ronny