The code is shown as follows:
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{pst-circ}
\begin{document}
\begin{center}
\begin{pspicture}[showgrid=true](3,2)
\pnodes(0,1){A}(3,1){B}
\resistor(A)(B){$R$}
\end{pspicture}
\end{center}
\end{document}
\usepackage{pst-circ}
and it shows "Undefined control sequence" at line 9 and 10.
How can I solve this?