[Rd] Problem with pdf graphics device

[Dominick Samperi]

This code does not work as expected:

pdf("foo.pdf")
x <- 1:20
y <- sin(x)
plot(x,y)
dev.off()

Instead of little circles at the points I get the letter 'q', and this
happens for the default pch, pch=1, pch=21. If I set pch='o' I
get the circles, but of course they are not centered. The problem
occurs with pdf viewer and with printing under Linux,
R 2.10.0.

Everything works as expected if I use other display devices.