Extract the +(plus) symbol from newtxmath

Question

I want to extract the plus symbol + from the newtx(which included newtxmath) package. But I want to just extract this symbol into my document, not to include the entire package (which leads to a conflict). How can I do this? For example, it seems it should be written as something like \DeclareMathSymbol{+}{...}{...}{...} to redefine the + symbol, but how can I get the font-family name of newtxmath? I checked the package document, but can't find it. At the same time, I also checked the newtxmath.sty, but hardly to understand. Need help.

Heiko Oberdiek · Accepted Answer · 2017-02-18T12:37:37.490

7

The important lines from newtxmath.sty for the redefinition of the plus sign in math are the lines with \DeclareMathSymbol{+} and the definitions for the symbol font lettersA.

In addition, the font definition file untxmia.fd uses \if switches that reflects the options libertine, minion, and cochineal.

\documentclass{article}

\mathchardef\OldPlus=\mathcode`\+

\makeatletter
\newif\iftx@libertine
\newif\iftx@minion
\newif\iftx@coch
\makeatother
\DeclareSymbolFont{lettersA}{U}{ntxmia}{m}{it}
\SetSymbolFont{lettersA}{bold}{U}{ntxmia}{b}{it}
\DeclareMathSymbol{+}{\mathbin}{lettersA}{253}

\begin{document}
\begin{tabular}{ll}
  Old: & $\OldPlus$\\
  New: & $+$
\end{tabular}
\end{document}

The case of the minus sign or \times is different. Here, package newtxmath redefines the standard symbol font symbols. Therefore, this font is renamed to NTXsymbols in the following example in order to avoid changes of other letters:

\documentclass{article}
\usepackage{booktabs}

\mathchardef\OldPlus=\mathcode`\+
\mathchardef\OldMinus=\mathcode`\-
\let\OldTimes\times

\makeatletter
\newif\iftx@libertine
\newif\iftx@minion
\newif\iftx@coch
\makeatother
\DeclareSymbolFont{lettersA}{U}{ntxmia}{m}{it}
\SetSymbolFont{lettersA}{bold}{U}{ntxmia}{b}{it}
\DeclareMathSymbol{+}{\mathbin}{lettersA}{253}

\DeclareSymbolFont{NTXsymbols}{OMS}{ntxsy}{m}{n}
\SetSymbolFont{NTXsymbols}{bold}{OMS}{ntxsy}{b}{n}
\DeclareMathSymbol{-}{\mathbin}{NTXsymbols}{0}
\DeclareMathSymbol{\times}{\mathbin}{NTXsymbols}{2}

\begin{document}
\begin{tabular}{ll}
  Old & New \\
  \midrule
  $\OldPlus$ & $+$ \\
  $\OldMinus$ & $-$ \\
  $\OldTimes$ & $\times$ \\
\end{tabular}
\end{document}

edited Feb 18 '17 at 12:37

answered Feb 18 '17 at 03:56

Heiko Oberdiek

271,626

Thanks! How can I mimic this way to redefine - and \times? I opened newtxmath.sty but can't find the definition of - or \times. Is there an encode table to see which character is corresponding to which encode? – Eric Feb 18 '17 at 04:48
@Eric See updated answer. – Heiko Oberdiek Feb 18 '17 at 09:16
@HeikoOberdiek I can compile successfully but seems LaTeX can't get the font of $-$ and $\times$, they look like traditional Computer Modern style symbols. (So the - looks rounded-corner and apparently longer then the +). My environment: I use XeLaTeX and mtpro2 now. I have installed the newtx package(the latest version) but don't usepackage them. The + behaves successfully. – Eric Feb 18 '17 at 10:17
@Eric Have you loaded mtpro2 before or after the redefinitions? – Heiko Oberdiek Feb 18 '17 at 11:18
Before. I put my test code to here (ps: the site doesn't support XeLaTeX.) – Eric Feb 18 '17 at 11:34
@HeikoOberdiek I can change the command \DeclareSymbolFont{NTXsymbols}{OMS}{ntxsy}{m}{n} to \DeclareSymbolFont{NTXsymbols}{OMS}{ntxsyddvskposdvk}{m}{n}(a non-existent family name) and pass the compiler. So maybe the reason I can't get the ntxsy font is that the compiler fail to load the ntxsy font? – Eric Feb 18 '17 at 11:57
@Eric In the answer, only symbols, the first argument of \DeclareSymbolFont is changed to NTXsymbols. The font mapping must be the same. Otherwise, you get a different font or a default font, if the font does not exist. – Heiko Oberdiek Feb 18 '17 at 12:39

score 6 · Answer 2 · edited Apr 13 '17 at 12:36

In case you do not wish to use a maths alphabet up for a single symbol (it is not hard to plough through the 16 available), you can define a macro to access the symbol by tweaking egreg's answer and the relevant commands from pifont. Combining this with the information from Heiko Oberdiek's answer:

\documentclass{article}
% ateb egreg: https://tex.stackexchange.com/a/14406/
\usepackage{pifont}
\makeatletter
\newcommand\Pimathsymbol[3][\mathord]{%
  #1{\@Pimathsymbol{#2}{#3}}}
\def\@Pimathsymbol#1#2{\mathchoice
  {\@Pim@thsymbol{#1}{#2}\tf@size}
  {\@Pim@thsymbol{#1}{#2}\tf@size}
  {\@Pim@thsymbol{#1}{#2}\sf@size}
  {\@Pim@thsymbol{#1}{#2}\ssf@size}}
\def\@Pim@thsymbol#1#2#3{%
  \mbox{\fontsize{#3}{#3}\Piitsymbol{#1}{#2}}}
% ateb Heiko Oberdiek: https://tex.stackexchange.com/a/354435/
\newif\iftx@libertine
\newif\iftx@minion
\newif\iftx@coch
% pifont.sty
\newcommand{\Piitfont}[1]{\fontfamily{#1}\fontencoding{U}%
\fontseries{m}\fontshape{it}\selectfont}
\newcommand{\Piitsymbol}[2]{{\Piitfont{#1}\char#2}}
\makeatother
\newcommand{\newplus}{\Pimathsymbol[\mathbin]{ntxmia}{253}}

\begin{document}

\[
      + \newplus
\]


\end{document}

Extract the +(plus) symbol from newtxmath

2 Answers2

Linked