13

I need to plot f(x) = 1 / x in LaTeX and am trying to with Tikz. I haven't found a way to set the vertical range, so the values go out of bound around x=0.

Using gnuplot directly doesn't seem to be an option because the fix presented here fails.

\begin{frame}
    \begin{tikzpicture}
        \draw[->] (-10, 0) -- (10, 0) node[right] {$x$};
        \draw[->] (0, -10) -- (0, 10) node[above] {$y$};
        \draw[color=red, domain=-10:10] plot[id=x] function{1/x} node[right] { $f(x) = x$ };
    \end{tikzpicture}
\end{frame}

I'm not set on Tikz, if there are other options I am open to them.

Community
  • 1
Otto Allmendinger
  • 413

3 Answers3

15

The pgfplots package has a plot drawing function that takes the parameter restrict y to domain. It takes care of the clipping and doesn't connect the points on the left and right of the singularity.

\documentclass{standalone}

\usepackage{pgfplots}

\begin{document}

  \begin{tikzpicture}
    \begin{axis}[
        restrict y to domain=-10:10,
        samples=1000,
        minor tick num=1,
        xmin = -10, xmax = 10,
        ymin = -10, ymax = 10,
        unbounded coords=jump,
        axis x line=middle,
        axis y line=middle]

      \addplot[mark=none, domain=-10:10] {(1-x)/(x^2-1)};
    \end{axis}
  \end{tikzpicture}

\end{document}

enter image description here

Philipp
  • 3,815
Otto Allmendinger
  • 413
13

With TikZ version 2 :

\documentclass{article}    
\usepackage{tikz}

\begin{document}

      \begin{tikzpicture}[scale=.5] 
        \draw[->] (-10, 0) -- (10, 0) node[right] {$x$};
        \draw[->] (0, -10) -- (0, 10) node[above] {$y$};
        \draw[color=red, domain=-10:-0.1,samples=200] plot[id=x1] function{1/x};
        \draw[color=red, domain=0.1:10,samples=200] plot[id=x2] function{1/x} node[below right = 6pt] { $f(x) =1/x$ };
    \end{tikzpicture}

\end{document}

enter image description here

Alain Matthes
  • 95,075
  • You can use gnuplot but not with gnuplottex. You can see the manual to see how to plot a function with gnuplot. After you can try pgfplots or tkz-fct. – Alain Matthes Jun 16 '11 at 16:37
  • doesn't work here: ! Number too big. \pgftemp@y. I'm using the beamer package – Otto Allmendinger Jun 16 '11 at 16:49
  • @Otto Allmendinger Altermundus example compiles on my system (TeX Live 2009). It also compiles if I change the documentclass to beamer. – N.N. Jun 16 '11 at 17:46
  • @Otto Allmendinger What is your version of pgfmath ? You can also modify the domains : -10:-0.1 and 0.1:10 – Alain Matthes Jun 16 '11 at 17:51
  • @Otto Allmendinger the last version is better I change the domains and remove the clip and put at the right place the name of the function. – Alain Matthes Jun 16 '11 at 18:00
  • @Altermundus: I took the pgfplots route anyway, see my answer. Thanks for your answer though. – Otto Allmendinger Jun 16 '11 at 18:39
  • @Otto Allmendinger pgfplots is a very fine package. restrict y to domain=-10:10is equivalent to a clip but unbounded coords=jump is a very fine option ! – Alain Matthes Jun 16 '11 at 18:55
0

What I tend to do is to clip all the graphs to match the same dimensions given by coordinate axes or grid. In your case, adding a line

\clip (-10,-10) rectangle (10,10);

before the draw function would prevent the graph from being drawn any further than wanted.

JoonasD6
  • 322