Creating a custom math symbol from scratch

Question

I want to use a special symbol from the Comprehensive LaTeX Symbol List called \diamondtimes. Unfortunately, when I include the MnSymbol package that provides this symbol, it also affects how other things look like. Since I need only this single symbol, is there any way to design it from scratch so that I don't have to include any extra packages?

Maybe it can be build by adding something on top of the standard \diamond symbol? In fact, I want the diamond produced by \diamondtimes to be the same size as \diamond, since I plan to use both.

Update: Since it has such a simple shape, I would prefer to make it from scratch (or put something on top of \diamond). Here is the original code from Sym-Geometric.mf:

beginoperator(med_op_size#, 1); "medium diamond times";
  pickup rule_pen;
  r := w/2 - side_bearing;
  draw square(centre, r / sqrt(2), 45);
  draw (centre + sqrt .5 * r * dir  45) -- (centre + sqrt .5 * r * dir 225);
  draw (centre + sqrt .5 * r * dir 135) -- (centre + sqrt .5 * r * dir 315);
endchar;

What language is this in and can I just reuse this somehow?

See http://tex.stackexchange.com/questions/132453/typing-following-notation-in-latex/132456#132456 for how to get a MNSymbol into your font — Steven B. Segletes, Dec 04 '13 at 16:44
I just found this post: http://tex.stackexchange.com/questions/36006/how-can-i-use-a-symbol-provided-by-a-package-without-changing-the-entire-mathema/ and I'm trying to follow the instructions. — Māris Ozols, Dec 04 '13 at 16:52
The language is indeed metafont, but this extract contains commands that are not in standard metafont. Presumably these are macros defined in some file in the MnSymbol package. However, it is easy to deduce what is going on if one knows metafont: A square is drawn, rotated 45 degrees, and then the two crossing lines are drawn. — Dan, Dec 05 '13 at 02:10

egreg · Accepted Answer · 2013-12-04T17:44:30.547

7

Rotate \boxplus by 45 degrees:

\documentclass{article}
\usepackage{graphicx,amsmath,amssymb}
\DeclareRobustCommand{\diamondtimes}{%
  \mathbin{\text{\rotatebox[origin=c]{45}{$\boxplus$}}}%
}

\begin{document}
$a\diamondtimes b$

$a\times b$
\end{document}

enter image description here

For a smaller version and an empty diamond (note that \diamond already exists, but gives a much smaller symbol):

\documentclass{article}
\usepackage{graphicx,amsmath,amssymb}
\DeclareRobustCommand{\diamondtimes}{%
  \mathbin{\text{\scalebox{.75}{\rotatebox[origin=c]{45}{$\boxplus$}}}}%
}
\DeclareRobustCommand{\bdiamond}{%
  \mathbin{\text{\scalebox{.75}{\rotatebox[origin=c]{45}{$\Box$}}}}%
}
\begin{document}
$a\diamondtimes b$

$a\bdiamond b$
\end{document}

enter image description here

edited Dec 04 '13 at 17:44

answered Dec 04 '13 at 17:05

egreg

1,121,712

Is there a way to make it a bit smaller and also to have a \diamond symbol of the same size? – Māris Ozols Dec 04 '13 at 17:10
A beautiful solution. But might it not be better to define the new symbol once, store it in a box register (or several, using \mathchoice for various sizes) and then \copy the box each time the symbol is used? – jvarilly Dec 04 '13 at 19:12
@jvarilly: I'm not familiar with these commands. Could you give some pointer on how to use them? – Māris Ozols Dec 04 '13 at 23:09
@jvarilly With the box approach the symbol wouldn't change size according to \small, \footnotesize and the like. – egreg Dec 04 '13 at 23:11

score 5 · Answer 2 · edited Apr 13 '17 at 12:35

Mimicing the procedure depicted at Typing Following notation in Latex, I was able to determine that \diamondtimes was part of MnSymbolC font set. Then, using the fonttable package (uncomment 2 lines in MWE), I found the symbol number to be 125. Then, I just changed the name and numbers from that example to get this one.

\documentclass{article}

\DeclareFontFamily{U} {MnSymbolC}{}

\DeclareFontShape{U}{MnSymbolC}{m}{n}{
  <-6> MnSymbolC5
  <6-7> MnSymbolC6
  <7-8> MnSymbolC7
  <8-9> MnSymbolC8
  <9-10> MnSymbolC9
  <10-12> MnSymbolC10
  <12-> MnSymbolC12}{}
\DeclareFontShape{U}{MnSymbolC}{b}{n}{
  <-6> MnSymbolC-Bold5
  <6-7> MnSymbolC-Bold6
  <7-8> MnSymbolC-Bold7
  <8-9> MnSymbolC-Bold8
  <9-10> MnSymbolC-Bold9
  <10-12> MnSymbolC-Bold10
  <12-> MnSymbolC-Bold12}{}

\DeclareSymbolFont{MnSyC} {U} {MnSymbolC}{m}{n}
%\Decl@Mn@Char\diamondtimes             {MnSyC}{\mathbin}
\DeclareMathSymbol{\diamondtimes}{\mathbin}{MnSyC}{125}

%\usepackage{fonttable}
\begin{document}
%\fonttable{MnSymbolC10}
$a \diamondtimes b$
\end{document}

enter image description here

Creating a custom math symbol from scratch

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