[Tex/LaTex] \widecheck like \widehat

fontssymbols

The question "Is there a way to do an "upside down" \widehat?" indicates that \widecheck is available in the mathabx package, but unfortunately, that package also changes the font style.

Can we define \widecheck by ourselves?

Best Answer

I did not know if it would be this easy, but it turned out so. I took my revised answer at Really wide hat symbol for \reallywidehat and made two simple changes:

  1. I changed all occurences of "hat" to "check"

  2. I changed the final \stackon argument from \tmpbox to \scalebox{-1}{\tmpbox}.

That was it. Here it is:

\documentclass{article}
\usepackage{scalerel,stackengine}
\stackMath
\newcommand\reallywidecheck[1]{%
\savestack{\tmpbox}{\stretchto{%
  \scaleto{%
    \scalerel*[\widthof{\ensuremath{#1}}]{\kern-.6pt\bigwedge\kern-.6pt}%
    {\rule[-\textheight/2]{1ex}{\textheight}}%WIDTH-LIMITED BIG WEDGE
  }{\textheight}% 
}{0.5ex}}%
\stackon[1pt]{#1}{\scalebox{-1}{\tmpbox}}%
}
\parskip 1ex
\begin{document}

$\reallywidecheck{zbcdefghijklm}$

$\reallywidecheck{zbcdefghijk}$

$\reallywidecheck{zbcdefghi}$

$\reallywidecheck{zbcdefg}$

$\reallywidecheck{zbcde}$

$\reallywidecheck{zbc}$

$\reallywidecheck{zb}$

$x\cdot\reallywidecheck{a_1+a_2}\cdot y$

\end{document}

enter image description here

Best of all, it avoids the use of mathabx, which resets a lot of math symbols.