How to insert a triangle/rectangle with plus sign in it (abstract algebra operators)?

Question

To insert the abstract algebra operators, I tried:

\documentclass{article}
\usepackage{stackengine}
\usepackage{scalerel}
\newlength\triwidth
\newcommand\tridelt[1]{%
  \setlength\triwidth{\widthof{#1\ }}%
  \stackengine{-.1\triwidth}{#1\ }%
    {\scaleto{\Delta}{1\triwidth}}{O}{c}{F}{F}{L}%
}
\begin{document}

\begin{equation}
   C = A \tridelt{+} B, C = A \tridelt{x} B
\end{equation}

\end{document}

as in

Triangle with text in it

but the result looks ugly, how to fix it?

Is there some reason for not using the TikZ solutions from https://tex.stackexchange.com/questions/123147/triangle-with-text-in-it? — John Kormylo, Apr 27 '17 at 14:40
See also https://tex.stackexchange.com/questions/254509/spacing-in-math-equation-latextikz — John Kormylo, Apr 27 '17 at 14:50

score 7 · Answer 1 · answered Apr 27 '17 at 15:19

The symbols can be found in the in the Comprehensive LaTeX symbols list.

\usepackage{stix}

\begin{equation}
  \triangleplus \triangleminus \triangletimes 
\end{equation}

As shown above, this package provides lots of symbols that can be used in abstract algebra (\boxplus \boxminus \boxtimes).

score 3 · Answer 2 · edited May 02 '17 at 03:24

Into the triangle you can put any symbols.

\documentclass{article}
\usepackage{mathtools}
\usepackage{mathptmx}
\usepackage{stackengine}
\usepackage{scalerel}
\usepackage{xcolor}
\newcommand\trianglesignx[1][2.3ex]{%
  \renewcommand\stacktype{L}%
  \scaleto{\stackon[0.7pt]{\color{black}$\triangle$}{\tiny $\times$}}{#1}%
}
\newcommand\trianglesignplus[1][2.3ex]{%
  \renewcommand\stacktype{L}%
  \scaleto{\stackon[0.7pt]{\color{black}$\triangle$}{\tiny $\times$}}{#1}%
}
\begin{document}
\[\alpha \trianglesignx f(x,y)=M-M_{\alpha} \trianglesignplus\]
\end{document}

EDIT (as requested in comments):

I made the following changes in the code:

Added \mathbin for proper spacing around the binary operators. See here for more details.
Removed \color{black} -- not sure what that is for.

Code:

\documentclass{article}
\usepackage{mathtools}
\usepackage{mathptmx}
\usepackage{stackengine}
\usepackage{scalerel}
\usepackage{stix}
\newcommand\trianglesignx[1][2.3ex]{%
    \renewcommand\stacktype{L}%
    \mathbin{%
    \scaleto{\stackon[0.7pt]{$\triangle$}{\tiny $\times$}}{#1}%
}}
\newcommand\trianglesignplus[1][2.3ex]{%
    \renewcommand\stacktype{L}%
    \mathbin{%
    \scaleto{\stackon[0.7pt]{$\triangle$}{\tiny $+$}}{#1}%
}}
\begin{document}
    Custom symbols:
    \[\alpha \trianglesignx f(x,y)=M-M_{\alpha} \trianglesignplus M_{\alpha}\]

    Symbols from \verb!stix! package: 
    \[\alpha \triangletimes f(x,y)=M-M_{\alpha} \triangleplus M_{\alpha}\]
\end{document}

Hi, what's the use of \color{black}, and is the second one supposed to be + instead of \times? Cause I'm not getting the output you're showing with the above code — Troy, Apr 29 '17 at 09:43
I think you should also include \mathbin to get proper spacing around the triangle operators. :) — Troy, Apr 29 '17 at 10:10
I did not put the times and the symbol + why did I want to make it clear that within the triangle can put anything? I was hoping you would have appreciated my work. Could you edit my answer including the command \mathbin. For six months I'm signed up on TeX.SE and I only put two negative votes. — Sebastiano, Apr 30 '17 at 20:07
For the record, I'm not the one who downvoted your answer.. — Troy, May 01 '17 at 01:36

How to insert a triangle/rectangle with plus sign in it (abstract algebra operators)?

2 Answers2