# [Tex/LaTex] How to code long down arrow in equations

arrowsequations

I want to design an equation which includes a long down arrow and long up arrow. I'm having just down arrow which is short. I need some help.

Just to practice with tikz-cd; the first diagram is in two versions, one with long arrows also in the first half, the second one with shorter arrows where long ones are not needed (just pass over an empty column for lengthening the arrows in the right half).

A similar trick could be used for the second diagram.

\documentclass{article}

\usepackage{amsmath}
\usepackage{tikz-cd}

\DeclareMathOperator{\Frob}{Frob}

\begin{document}

\begin{equation*}
\begin{tikzcd}[column sep=6pc]
C_{(f^{p^n})} \arrow{r} \arrow{d}{(\varphi^n)^*} &
k(Z_{f^{(p^n)}}) \arrow{r}{(i_{F^{(p^n)},f^{(p^n)}})^{-1}} \arrow{d}{(\varphi^n)^*} &
k(X_{F^{(p^n)}}) \arrow{d}{(\varphi^n)^*} \\
C_f \arrow{r} &
k(Z_f) \arrow{r}{(i_{F,f})^{-1}} &
k(X_F)
\end{tikzcd}
\end{equation*}
Another diagram
\begin{equation*}
\begin{tikzcd}[column sep=3.5pc]
K \arrow{r}{(\Frob_K)^n} & K^{p^n} \arrow[hookrightarrow]{r} & K \\
k(x) \arrow{r}{(\Frob_{k(x)})^n} \arrow{u} &
k(x)^{p^n} \arrow{u} \arrow[hookrightarrow]{r} & k(x) \arrow{u}
\end{tikzcd}
\end{equation*}

\end{document}