答案1
求解隐式定义方程。运行pdflatex --shell-escape
\documentclass[pstricks]{standalone}
\usepackage{pst-func}
\usepackage{auto-pst-pdf}
\begin{document}
\begin{pspicture*}(-5,-2.5)(5.5,3.5)
\pscircle(0,0){1}%
%\psaxes{->}(0,0)(-5,-2)(5.2,3)%
\multido{\rA=0.01+0.2}{5}{%
\psplotImp[linewidth=1pt,linecolor=blue,polarplot,
stepFactor=0.2,algebraic](-6,-6)(6,2.4){%
(r^2-1/r)*(sin(phi/57.296)^2)-\rA}}%
\uput*[45](0,2){$f(r,\phi)=\left(r^2-\frac{1}{r}\right)\cdot\sin^2\phi=0$}
\psline[arrowscale=2,linewidth=1.5pt,linecolor=black!40]{->}(-4,-1.5)(4,-1.5)
\end{pspicture*}
\end{document}