Plotting a reciprocal of a sine function in tikz + pgfplots

Question

This is my code at the moment:

% Rest of document omitted brevity...
\subsection*{f(x) = cosec(x)}
\begin{tikzpicture}
\begin{axis}[every axis plot post/.append style={
  mark=none,
  domain=0:360,
  samples=500,
  smooth}, % All plots: 50 samples, smooth, no marks
  axis x line=middle,
  axis y line=center,
  xmin=0,
  xmax=360,
  ymin=-1,
  ymax=1,
  enlargelimits=upper] % extend the axes a bit to the right and top
  \addplot {1 / sin(x)};
\end{axis}
\end{tikzpicture}
% Rest of document omitted brevity...

This looks right to me, however, when I try and compile, I get: C:/Users/Todd/Dropbox/Homework/Notes/A-level_Maths/Core 3/Graphs/Graphs.tex:111: Dimension too large. [\end{axis}]

When I change \addplot {1 / sin(x)}; to \addplot {sin(x)}; the document compiles without any issues. What am I doing wrong?

Answer 1

Some remarks about what are you trying to achieve:

• Consider using degrees as an argument for trigonometric functions via deg(x)-pgfplots function.
• After using deg(x) the domain and range of x-axes should be rescaled.
• Don't forget the \pgfplotsset{compat=1.7} in document preamle. =)
• Use cosec(x) function instead of 1 / sin(x).

Finally we've got (included all, wrapped in standalone):

\documentclass{standalone}
\usepackage[english]{babel}
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}
\begin{document}
\begin{tikzpicture}
\begin{axis}[every axis plot post/.append style={
      mark=none,
      domain=0:10,
      samples=500,
      smooth}, % All plots: 50 samples, smooth, no marks
  axis x line=middle,
  axis y line=center,
  xmin=0,
  xmax=10,
  ymin=-10,
  ymax=10,
  enlargelimits=upper] % extend the axes a bit to the right and top
  \addplot {cosec(deg(x))};
\end{axis}
\end{tikzpicture}
\end{document}

And the result:

Answer 2

Problem is on x=k*pi, 1/sin(x) is undefined (or as your error suggests "too large" because the package plots it numerically) . You can solve this problem by using restrict y to domain:

\begin{tikzpicture}
\begin{axis}[every axis plot post/.append style={
  restrict y to domain=-10:10,
  mark=none,
  domain=-360:360,
  samples=500,
  smooth}, % All plots: 50 samples, smooth, no marks
  axis x line=middle,
  axis y line=center,
  xmin=-360,
  xmax=360,
  ymin=-10,
  ymax=10,
  enlargelimits=upper] % extend the axes a bit to the right and top
  \addplot {1/sin(x)};
\end{axis}
\end{tikzpicture}