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I have tried without success to plot the curve of the chi-squared distribution. Is there a generous soul who can come to my rescue.

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Show what you've tried so far in form of a minimal example and add this to your question. –  Thorsten Donig Jan 12 '12 at 20:33
Why haven't you accepted an answer? –  Magpie Jan 22 '13 at 19:11

2 Answers 2

if you can use PSTricks, then it is easy. Run the example with xelatex


\psaxes[Dy=0.1,ticksize=0 3pt]{->}(0,0)(9.5,.6)


enter image description here

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Thanks for taking the time to answer my request but when I run the code I have this message of error: ! Package xkeyval Error: plotpoints' undefined in families ,pstricks,pst-grad ,pst-slpe,pst-node,pst-fun'. See the xkeyval package documentation for explanation. Type H <return> for immediate help. ... l.5 \psset{xunit=1.2cm,yunit=10cm,plotpoints=200} ? x Any help would be appreciated. Sincerly. –  Zbigniew Jan 18 '12 at 20:10
best result with texlive Unlike MiKTteX. Thank you to everyone. –  Zbigniew Jan 18 '12 at 20:21
You may have an outdated version of pstricks. Since you're using TeX Live, call tlmgr update --self --all from your terminal (command prompt). –  Werner Jan 18 '12 at 20:46
add \usepackage{pst-plot} to the preamble –  Herbert Jan 18 '12 at 20:57

If you can access gnuplot, you can try this. This is an adapted version of a gnuplot demo file.

enter image description here

    xlabel = $x$,
    ylabel = {Probability density},
    samples = 200,
    restrict y to domain = 0:0.5,
    domain = 0.01:15]
    \foreach \k in {1,...,8} {%
      \addplot+[mark={}] gnuplot[raw gnuplot] {%
        isint(x) = (int(x)==x);
        log2 = 0.693147180559945;
        set xrange [1.00000e-5:15.0000];
        set yrange [0.00000:0.500000];
        plot chisq(x,\k)};
    \addlegendentryexpanded{$k = \k$}}
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To see a solution with LuaLaTeX, see here. –  Azoun Jan 15 '12 at 1:07
The curve for the case $k=0$ is missing.This isn't exactly a surprise, because the chi-squared distribution isn't defined properly for $k=0$... I suggest you update the plot to drop the case $k=0$ from the legend. –  Mico Jan 14 at 8:28
@Mico Done. Thanks for the suggestion. –  cjorssen Jan 15 at 12:50

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