[Tex/LaTex] Writing on top of a long arrow

arrows

I want to make the arrow in the numerator longer, like the one in the denominator and write $x$ on top of it. I'm using the package mathtools.

\[
    H_{1}(K_1)=\frac{\textrm{ker}(R \xrightarrow{x} R)}{\textrm{im}(0 \longrightarrow R)} \cong \textrm{ker}(R \longrightarrow R)= \frac{R}{xR}.
\]

Best Answer

(memoir is unrelated, just my goto class)

\documentclass[a4paper]{memoir}
\usepackage{amsmath,amssymb}
\DeclareMathOperator\im{im}
\begin{document}
\[
H_1(K_1) = \frac{\ker(R\xrightarrow{x} R)}{\im(0\to R)}
\]
\end{document}

Related Solutions

[Tex/LaTex] How to draw a double-ended arrow between the numerator and denominator in a frac inside a sqrt, and an arrow labeled by an otimes pointing to that

A solution that uses calc to determine the position of the double arrow:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}
    \begin{tikzpicture}[execute at begin node = $\displaystyle, execute at end node   = $]
        \node (eq) {\sqrt{\frac{N}{p(1-p)}}};
        \draw[<->] ($(eq.north east)!.3!(eq.south east)$) to[in=0, out=0,distance=10] node[right] {\leftarrow\otimes} ($(eq.north east)!.7!(eq.south east)$);
    \end{tikzpicture}
\end{document}

enter image description here

Some adjustments to tailor it to your liking:

For a longer arrow, change \leftarrow to \longleftarrow
You can use colours by adding \color{}
The size of the bend of the double arrow is in distance=...
The vertical position of the arrowheads of the double arrow are the !.3! and !.7!
The horizontal position of the arrowheads of the double arrow can be adjusted by adding -(.4,0).

Example:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}
    \begin{tikzpicture}[execute at begin node = $\displaystyle, execute at end node   = $]
        \node (eq) {\sqrt{\frac{N}{p(1-p)}}};
        \draw[<->,red] ($(eq.north east)!.3!(eq.south east)-(.4,0)$) to[in=0, out=0,distance=20] node[right] {\color{blue}\longleftarrow \color{green}\otimes} ($(eq.north east)!.7!(eq.south east)$);
    \end{tikzpicture}
\end{document}

enter image description here

[Tex/LaTex] Uniform convergence symbol (arrow on top of arrow, same size)

If you don't need it in smaller math styles, then this could work...

\documentclass{article}
\usepackage{stackengine,graphicx}
\stackMath
\newcommand\frightarrow{\scalebox{1}[.4]{$\rightarrow$}}
\newcommand\darrow[1][]{\mathrel{\stackon[1pt]{\stackanchor[1pt]{\frightarrow}{\frightarrow}}{\scriptstyle#1}}}
\begin{document}
$A\darrow[n] B$
\end{document}

Here is a composite alternative

\documentclass{article}
\usepackage{stackengine,graphicx,amssymb}
\stackMath
\newcommand\frightarrow{\scalebox{1}[.3]{$\rule[.45ex]{2ex}{1.5pt}%
  \kern-.2ex{\blacktriangleright}$}}
\newcommand\darrow[1][]{\mathrel{\stackon[1pt]{\stackanchor[1pt]{\frightarrow}{\frightarrow}}{\scriptstyle#1}}}
\begin{document}
$A\darrow[n] B$
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] How to draw a double-ended arrow between the numerator and denominator in a frac inside a sqrt, and an arrow labeled by an otimes pointing to that

[Tex/LaTex] Uniform convergence symbol (arrow on top of arrow, same size)

Related Question