\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)
 matplot(xvals, cbind(gam1,gam2), type = "l", ylab = "gamma probability density",  ylim = c(0,1), main = "Gamma Probability Densities")
 text(.4, .7, "shape=1, scale=1", pos=4, col=1)
 text(3, .2, "shape=2, scale=1", pos=4, col=2)
\end{Sinput}
\end{Schunk}
