I'm looking for a way to illustrate Trapezoidal rule. I've seen this code to illustrate Riemann sums (Riemann sum with pgfplots -- can't seem to make graph look right) but I don't see how to adapt it.
\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.9}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
xtick={0,1,3,5,7,9,11,13,15,17},ytick={0,...,1.5},
xmax=18,ymax=1.2,ymin=0,xmin=0,
enlargelimits=true,
axis lines=middle,
clip=false,
domain=0:17,
axis on top
]
\addplot [draw=red, fill=red!10, ybar interval, samples=9, domain=1:17]
{x^-1}\closedcycle;
\addplot [draw=green, fill=green!10, ybar interval, samples=9, domain=17:1]
{x^-1}\closedcycle;
\addplot[smooth, thick,domain=1:17,samples=40]{x^-1};
\end{axis}
\end{tikzpicture}
\end{document}
Do you have any suggestion ?
