\begin{Schunk}
\begin{Sinput}
 x <- 0:10
 y <- dpois(x, lambda=1.3)
 par(mfcol=c(1,2))
 plot(x,y, type="h", lty=4, xlab=expression(x ~~ group("(",lambda==1.3,")")) , ylab="Probability")
 points(x,y, pch=16)
 y <- dpois(x, lambda=4.0)
 plot(x,y, type="h", lty=4, xlab=expression(x ~~ group("(",lambda==4.0,")")) , ylab="Probability")
 points(x,y, pch=16)
 par(mfcol=c(1,1))
\end{Sinput}
\end{Schunk}
