\begin{Schunk}
\begin{Sinput}
 xvals <- seq(0,10,length.out=1000)
 gam1 <- dgamma(xvals, shape=1, scale=1)
 gam2 <- dgamma(xvals, shape=2, scale= 1)
 plot(xvals, gam1, type="l", xlab="x",ylab="Gamma probability density",  ylim=c(0,1))
 lines(xvals, gam2, lty=2)
 text(.4, .7, "shape=1, scale=1", pos=4, col=1)
 text(3, .2, "shape=2, scale=1", pos=4, col=1)
\end{Sinput}
\end{Schunk}
