\begin{Schunk}
\begin{Sinput}
 par(mfcol=c(4,3))
 for ( j in 1:3){
   for ( i in 1:4 ){
    shape <- c(0.5,1,2,10)
    scale <- c(0.5,1,3)
    xrange <- seq(from = 0, to = scale[j]*20, by = 0.1)
    mainlabel<- paste("shape=",shape[i],",scale=", scale[j],sep="")
    xprob <- dgamma(xrange, shape = shape[i], scale = scale[j], log = FALSE)
    plot(xrange, xprob, type="l", main = mainlabel, xlab = "possible values of x", ylab = "probability of x")
   }
  }
\end{Sinput}
\end{Schunk}
