[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.

enter image description here

Best Answer

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}

enter image description here

Related Solutions

[Tex/LaTex] Long Right arrow appears broken

I find the horizontal spacing of the chemarrows in mathematical formulas surprisingly bad. It may well be that the spacing is adjusted to the use in chemistry. If you want an arrow with (approximately) the same length and spacing as a \longrightarrow, then you can use this code:

\documentclass{article}
\usepackage{amsmath,xspace}
\usepackage{chemarrow}
\newcommand{\lra}{\ensuremath{\mathrel{%
    \mkern1.5mu\textrm{\arro\symbol{71}}%
    \mkern-1.1mu\textrm{\arro\symbol{65}}%
    }}\xspace}

\begin{document}
Test \lra Result

Test $\longrightarrow$ Result
\end{document}

The xspace package is only needed for having \lra behave in the same way as $\lra$ (otherwise TeX wouldn't put a space after \lra). It is always a good idea to include an \xspace if you use \ensuremath in a macro that takes no arguments.

[Tex/LaTex] Dashed down arrow

Basic Solution:

Now sure exactly what problem you had with using \rotatebox, but it seems to work if used as \rotatebox{-90}{$\dashrightarrow$}:

enter image description here

Notes:

Depending on the actual application this might need to be raised vertically, and that can be down with \raisebox:
```
  \newcommand{\dashdownarrow}{\raisebox{2.0ex}{\rotatebox{-90}{$\dashrightarrow$}}}
```

If it is a binary/relational operator than you can enclose the symbol in \mathbin{}/\mathrel{}:

  \newcommand{\dashdownarrow}{\mathbin{\raisebox{2.0ex}{\rotatebox{-90}{$\dashrightarrow$}}}}

Use `\mathchoice` to auto resize:

As per Gonzalo Medina 's suggestion, to be able to use this for different math sizes such as in subscripts, you can use \mathchoice to ensure that the symbol also adjusts in size depending on the surrounding math environment:

enter image description here

Code:

\documentclass{article} 
\usepackage{amssymb} 
\usepackage{graphicx} 

\newcommand\dashdownarrowi{\mathchoice%
    {\rotatebox[origin=c]{-90}{$\displaystyle\dashrightarrow$}}%
    {\rotatebox[origin=c]{-90}{$\displaystyle\dashrightarrow$}}%
    {\rotatebox[origin=c]{-90}{$\scriptstyle\dashrightarrow$}}%
    {\rotatebox[origin=c]{-90}{$\scriptscriptstyle\dashrightarrow$}}%
} 

\newcommand{\dashdownarrow}{\mathrel{\dashdownarrowi}} 

\begin{document} 
    $A\dashdownarrow B\quad M_{A\dashdownarrow B}\quad L_{M_{A\dashdownarrow B}}$ 
\end{document}

Use `\text{}` for auto resizing (and change size):

egreg had provided a simpler way to get the same effect and that is by enclosing the symbol in \text{}, allows it to re size appropriately:

enter image description here

Notes:

In this version I added \scalebox so that you can make the symbol smaller -- adjust the scale factor to suit.
If you desire to move it vertically you can use \raisebox{<length>}{}.

Code:

\documentclass{article} 
\usepackage{amsmath} 
\usepackage{amssymb} 
\usepackage{graphicx} 

\newcommand\ddaaux{\rotatebox[origin=c]{-90}{\scalebox{0.70}{$\dashrightarrow$}}} 
\newcommand\dashdownarrow{\mathrel{\text{\ddaaux}}}

\begin{document} 
    $A\dashdownarrow B\quad M_{A\dashdownarrow B}\quad L_{M_{A\dashdownarrow B}}$ 
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Long Right arrow appears broken

[Tex/LaTex] Dashed down arrow

Basic Solution:

Notes:

Use \mathchoice to auto resize:

Code:

Use \text{} for auto resizing (and change size):

Notes:

Code:

Related Question

Use `\mathchoice` to auto resize:

Use `\text{}` for auto resizing (and change size):