What is a simple way to have \ll on top of \gg with equal size and vertically center aligned and have them work as a binary relation symbol like \lessgtr? The commands \underset and \overset cannot be used because they do not treat the two symbols equally, and they do not vertically center.
[Tex/LaTex] a simple way to create a binary relation symbol on top of another
math-moderelation-symbolssymbols
Related Solutions
Using \scalerel, one can make one argument match the vertical extent of another argument. The optional argument is a max-width constraint (in this case, I chose 2ex). Here's an example of the same code working on two different \somethinghuge arguments. In this case, I chose \mysymbol as a / sign.
\documentclass{article}
\usepackage{scalerel}
\def\mysymbol{/}
\begin{document}
\def\somethinghuge{\rule[-2.2ex]{2ex}{6ex}}
$\left( \somethinghuge \scalerel*[2ex]{\mysymbol}{\somethinghuge} b \right)$
\def\somethinghuge{\rule[-3.2ex]{2ex}{8ex}}
$\left( \somethinghuge \scalerel*[2ex]{\mysymbol}{\somethinghuge} b \right)$
\end{document}
Here's an equivalent syntax that would allow you to avoid typing \somethinghuge twice.
$\left( \scaleleftright[2ex]{.}{\somethinghuge}{\mysymbol} b \right)$
Here's a solution that builds the underbar with the help of picture mode.
\documentclass{article}
\usepackage{amsmath}
\usepackage{pict2e,picture}
\makeatletter
\newcommand{\pnrelbar}{%
\linethickness{\dimen2}%
\sbox\z@{$\m@th\prec$}%
\dimen@=1.1\ht\z@
\begin{picture}(\dimen@,.4ex)
\roundcap
\put(0,.2ex){\line(1,0){\dimen@}}
\put(\dimexpr 0.5\dimen@-.2ex\relax,0){\line(1,1){.4ex}}
\end{picture}%
}
\newcommand{\precneq}{\mathrel{\vcenter{\hbox{\text{\prec@neq}}}}}
\newcommand{\prec@neq}{%
\dimen2=\f@size\dimexpr.04pt\relax
\oalign{%
\noalign{\kern\dimexpr.2ex-.5\dimen2\relax}
$\m@th\prec$\cr
\noalign{\kern-.5\dimen2}
\hidewidth\pnrelbar\hidewidth\cr
}%
}
\makeatother
\begin{document}
$\alpha\precneq\beta_{\precneq}$ $\prec\preceq\precneq$
$\alpha\preceq\beta_{\preceq}$
\end{document}
Best Answer
You can try
substackI added
amsmathfor\lessgtrbut it also needed forsubstack. You may read more about this command in theamsmathdocumentation or in themathmodepaper. As @tohecz pointed out, one may need some spacing correction bymathrel. Furthermore i added a vertical correction with the optional argument of\\. This makes the symbol a little bit more like belonging together (and might be a thing of personal taste too).