\begin{Schunk}
\begin{Sinput}
 rate <- 1
 upper <- 10
 xvals <- seq(0, upper, by = 0.02)
 yvals1 <- dexp(xvals, rate = rate)
 plot(xvals, yvals1, type = "l", main = "", xlab = "x", ylab = "probability")
 text(0.7 * max(xvals), 0.7 * max(yvals1), label = bquote(f(x) == exp(-x)))
\end{Sinput}
\end{Schunk}
