在 TikZ 中绘制 \mapsto 箭头

Question

我想画一个像这样的长 \mapsto 状箭头：

\documentclass{article}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
    \node (sequence) at (0,0) {
        $\sqrt[4]{2} 
        \mapsto \sqrt[4]{2}\,i 
        \mapsto -\sqrt[4]{2} 
        \mapsto -\sqrt[4]{2}\,i$
    };
    \draw[|->,looseness=3] 
        (sequence.mid east) 
        to[out=0,in=0] (sequence.south east) 
        -- (sequence.south west) 
        to[out=180,in=180] (sequence.mid west);
\end{tikzpicture}

\end{document}

但是，这样不太美观。长箭的箭头太小，箭尾太大。

你能教我如何调整箭头吗？

Answer 1

\documentclass{article}
\usepackage{tikz}

\usetikzlibrary{arrows.meta}
\tikzset{|/.tip={Bar[width=.8ex,round]}}

\begin{document}

\begin{tikzpicture}
    \node (sequence) at (0,0) {
        $\sqrt[4]{2} 
        \mapsto \sqrt[4]{2}\,i 
        \mapsto -\sqrt[4]{2} 
        \mapsto -\sqrt[4]{2}\,i$
    };
    \draw[|->,looseness=3] 
        (sequence.mid east) 
        to[out=0,in=0] (sequence.south east) 
        -- (sequence.south west) 
        to[out=180,in=180] (sequence.mid west);
\end{tikzpicture}

\end{document}

Answer 2

另一个选择是使用内置mapsto箭头tikz-cd。这样做的好处是你不必猜测箭的长度：

\documentclass{article}
\usepackage{tikz-cd}

\begin{document}

\begin{tikzcd}[
  column sep=1em,
  every arrow/.style={draw,mapsto}
]
\sqrt[4]{2}\ar[r] & \sqrt[4]{2}\,i\ar[r] & -\sqrt[4]{2}\ar[r] & -\sqrt[4]{2}\,i
  \arrow[lll,rounded corners,to path={ -| ([xshift=2ex,yshift=-2.5ex]\tikztostart.east) -- ([xshift=-2ex,yshift=-2.5ex]\tikztotarget.west) |- (\tikztotarget) }]
\end{tikzcd}

\end{document}