# How to insert vertical cut in delta symbol?

How to insert vertical cut in delta symbol to denote divided difference?

This might be what you want. It can be adjusted if needs arise.

\documentclass{article}

\makeatletter
\DeclareRobustCommand{\divdiff}{\mathrel{\mathpalette\div@diff\relax}}
\newcommand{\div@diff}[2]{%
\mathstrut\ooalign{\hidewidth$\m@th#1|$\hidewidth\cr$\m@th#1\bigtriangleup$\cr}%
}
\makeatother

\begin{document}

$A\divdiff B_{x\divdiff y}$

\end{document}


An equilateral triangle with the bisector:

\documentclass{article}
\usepackage{amsmath}
\usepackage{pict2e}
\usepackage{color}
\makeatletter
\DeclareRobustCommand{\divdiff}{\mathrel{\text{\div@diff}}}
\newcommand{\div@diff}{%
\sbox\z@{$\m@th\bigtriangleup$}%
\setlength{\unitlength}{\wd\z@}%
\begin{picture}(1,0.69282)
\linethickness{.09ex}
\roundjoin
\polyline(0.1,0)(0.9,0)(0.5,0.69282)(0.1,0)(0.5,0)
\polyline(0.5,0.69282)(0.5,0)
\end{picture}%
}
\makeatother

\begin{document}

$A\divdiff B_{x\divdiff y}$

\end{document}


• Yes, it is almost ok, but the median should not cross the base. – Khirod Boruah Jul 1 '16 at 4:40
• @KhirodBoruah Does the new one appeal more to you? – egreg Jul 1 '16 at 9:44

Are you looking by chance for something like this one:

234B     ⍋  Apl Functional Symbol Delta Stile


Since it is an APL character, you can try the package APL from CTAN (it looks like a plain TeX package, but once you have the character, you can adapt it to use with LaTeX as well).

Alternatively, you can try to insert it directly from UNicode (given a UNicode font that supports this symbol).