函数拟合,不太好想
\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw[-latex] (-2,0) -- (2,0)node[right]{$x$};
\draw[-latex] (0,-1.8) -- (0,1.8)node[above]{$y$};
\draw[rounded corners] (0,0) ..controls (0.19,0.2) .. (0.4,1) ..controls(1.13,0.58).. (1.7,0)node[below]{$\pi$};
\draw[rounded corners] (0,0) ..controls (-0.19,0.2) .. (-0.4,1) ..controls(-1.13,0.58).. (-1.7,0)node[below]{$-\pi$};
\end{tikzpicture}
\end{document}
厉害