绘制卡方分布

Question

如何绘制上面的图片？

这个问题是关于；

• 绘制卡方分布
• 遮蔽分布区域
• 注释图形

Answer 1

\documentclass[pstricks]{standalone}
\usepackage{pst-func}

\begin{document}

\psset{xunit=1.2cm,yunit=15cm,plotpoints=200}
\begin{pspicture*}(-0.75,-0.1)(10,0.35)
\pscustom[fillstyle=solid,fillcolor=red!30,linestyle=none]{%
    \psline(6,0)(6,0.06)
    \psChiIIDist[linewidth=1pt,linecolor=red,nue=3.5]{6}{9}
    \psline(9,0)
}
\psline(6,-0.01)(6,0.2)
\psChiIIDist[linewidth=1.5pt,linecolor=red,nue=3.5]{0.01}{9}
\psaxes[Dy=0.1,labels=none,ticks=none]{->}(0,0)(9.5,0.3)
\pcline[nodesepB=5pt]{<-}(0,0.15)(6,0.15)\ncput*{\footnotesize Not Refecting of $H_0$}
\pcline[nodesepA=5pt]{->}(6,0.15)(9.5,0.15)%
  \ncput*{\footnotesize\shortstack{Refecting\\Region of\\$H_0$}}
\rput(6,-0.025){\footnotesize Critical $\chi^2=2.547$}
\rput(8,-0.05){\footnotesize Calculated $\chi^2=5.147$}
\psline{->}(8,-0.03)(8,0)
\psframe*[linecolor=black,opacity=0.1](-0.75,-0.1)(10,0.35)
\end{pspicture*}

\end{document}