\begin{Schunk}
\begin{Sinput}
 x <- seq(-4, 4, length.out = 1000)
 px1 <- dt(x, df = 1)
 px2 <- dt(x, df = 5)
 px3 <- dt(x, df = 20)
 px4 <- dt(x, df = 100)
 plot(x, px1, xlab = "t", ylab = "probability density of t", type = "l", ylim = c(0, 
      0.5))
 lines(x, px2, lty = 2)
 lines(x, px3, lty = 3)
 lines(x, px4, lty = 4)
 legend("topright", legend = c("df=1", "df=5", "df=20", "df=100"), lty = 1:4)
\end{Sinput}
\end{Schunk}
