Extensible leftarrow accent above math symbols

by murray   Last Updated September 11, 2019 22:23 PM

What better ways are there than what I show below for using a left arrow as a math accent to go over single and groups of symbols, and in a harmonious way?

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{newtxtext,newtxmath}
\usepackage{accents}
\usepackage{extarrows}

\linespread{1.1} % just to display output here more clearly

\newcommand{\reverse}[1]{\accentset{\leftarrow}{#1}}
\newcommand{\xreverse}[1]{\accentset{\xlongleftarrow{}}{#1}}
\newcommand{\longreverse}[1]{\overleftarrow{#1}}

\begin{document}

Accent single character with left arrow:

\smallskip

$\reverse{\sigma}$ \quad Arrow too short, too light, too small?

$\longreverse{\sigma}$ \quad Arrow too long and heavy!

\medskip

Accent multiple characters with left arrow:

\smallskip

$\xreverse{\sigma \ast \tau}$ \quad Use \verb!\xreverse!: arrow definitely too short. 

$\longreverse{\sigma \ast \tau}$ \quad Use \verb!\longreverse!: arrow long enough, but perhaps too heavy?

\bigskip

Want to use  better arrows in the alternative to \dots
\[(\sigma \ast \tau)^{\leftarrow} \simeq \reverse{\tau} \ast \reverse{\sigma}
\]
\dots that instead puts the long left arrow over the whole group of 3 symbols:

\begin{itemize}

\item $\longreverse{\sigma \ast \tau} \simeq \reverse{\tau} \ast \reverse{\sigma}$ \quad Use \verb!\longreverse! on left, \verb!\reverse! on right.

\item $\longreverse{\sigma \ast \tau} \simeq \longreverse{\tau} \ast \longreverse{\sigma}$ \quad Use \verb!\longreverse! for all.

\end{itemize}

\end{document}

leftarrow accents

I'd strongly prefer a method that avoids using TikZ or other drawing methods. And I need a method that will be relatively robust when a different font family (e.g., lucidabr, mathtimepro2) is used insstead of newtx.

I am aware of Configurable and Extensible Accents (Arrows, Dots, Vectors) and the item Dashed left arrow over symbol that is referenced by the accepted answer to it.

Tags : arrows accents


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