How to load a single symbol for my LaTeX document [duplicate]

Question

I simply want to use the \multimapboth symbol, which belongs to the \txfonts package; however I don't want to install this package, as it changes some formatting on my document... How can I do this? Thank you in advance.

EDIT: I'm looking for something like the answer to this question, just don't know how can I find more details about my symbol...

Answer 1

Add these to your preamble.

\DeclareSymbolFont{symbolsC}{U}{txsyc}{m}{n}
\SetSymbolFont{symbolsC}{bold}{U}{txsyc}{bx}{n}
\DeclareFontSubstitution{U}{txsyc}{m}{n}
\DeclareMathSymbol{\multimapboth}{\mathrel}{symbolsC}{"13}

Code:

\documentclass{article}
%\usepackage{txfonts}
\DeclareSymbolFont{symbolsC}{U}{txsyc}{m}{n}
\SetSymbolFont{symbolsC}{bold}{U}{txsyc}{bx}{n}
\DeclareFontSubstitution{U}{txsyc}{m}{n}
\DeclareMathSymbol{\multimapboth}{\mathrel}{symbolsC}{"13}
\begin{document}
  $\multimapboth$
\end{document}

How do we know what to do?

Look in to the txfonts.sty for the definition of \multimapboth. It is something like

 \re@DeclareMathSymbol{\multimapboth}{\mathrel}{symbolsC}{"13}

Now you need the definition of symbolsC. Look for it in the same file.

%%%%%%%%%%%%%%%%%%
% Math Symbols C %
%%%%%%%%%%%%%%%%%%

\DeclareSymbolFont{symbolsC}{U}{txsyc}{m}{n}
\SetSymbolFont{symbolsC}{bold}{U}{txsyc}{bx}{n}
\DeclareFontSubstitution{U}{txsyc}{m}{n}

Put both together and you are good to go.