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You might know that in large part of continental Europe, decimal mark is comma instead of dot. I am writing a really huge document and I would like to switch between them easily from one point, e.g.
\newif\comma
\commatrue
\ifcomma{
???
}
\pi = 3???14
I am aware that all decimal mark dots should be replaced by something else, but what? I am opening contest for a most elegant solution for the problem.
The following example sets the numbers in math mode. That allows an easy "redefinition" of the comma or dot to produce a dot or comma.
Syntax:
\num{...} takes a number with dot or comma and outputs the number according to switch \ifnumcomma.\numcommatrue if active, then \num outputs a comma, with \numcommafalse, the output is a dot.The definition can be used for both plain TeX and LaTeX. The example contains a testing part for plain TeX:
\mathchardef\NumMathCodeDot=\mathcode`\. %
\mathchardef\NumMathCodeComma=315 % \mathord, not \mathpunct
\newif\ifnumcomma
\def\num#1{%
\leavevmode
\begingroup
\ifnumcomma
\mathcode`\.=\NumMathCodeComma
\mathcode`\,=\NumMathCodeComma
\else
\mathcode`\.=\NumMathCodeDot
\mathcode`\,=\NumMathCodeDot
\fi
\ifmmode
#1%
\else
\mathsurround=0pt %
$#1$%
\fi
\endgroup
}
% Testing (plain TeX)
\numcommatrue
\num{3.14} + \num{1,23}
\numcommafalse
\num{3.14} + \num{1,23}
\bye
Remarks:
siunitx is available, use it, because it is much more powerful and configurable. Then \num can be left in the code, but the definition then comes from siunitx. And \num is configured there.
\num since this name is already widely employed by users of the siunitx package.
– Mico
Sep 18 '13 at 15:49
siunitx (why it is not available for plain TeX?), then he does not need the code of this answer, because siunitx is much more powerful.
– Heiko Oberdiek
Sep 18 '13 at 15:51
siunitx package is loaded. Regarding the non-availability of siunitx for PlainTeX, I suspect that Joseph Wright can/should give the authoritative answer. :-) I suspect, though, that it might have something to do with much of the code in siunitx being written in LaTeX3...
– Mico
Sep 18 '13 at 16:03
siunitx. I found it so powerful, I will risk even longer compilation of 200 page document.
– Pygmalion
Sep 18 '13 at 16:54
Decimal numbers in TeX can be input either with a period or a comma:
\hsize=10,5cm
is understood as well as
\hsize=10.5cm
However, this is about decimal numbers passed to TeX when required by its syntax rules. Printing numbers is a different matter, because TeX will print whatever you decide to.
So, if you define
\def\PI{3.14159}
and type \PI in your document, TeX will dutifully output
3.14159
In order to ensure uniformity across your document, you have to input your numbers in a different way:
\newif\ifcomma % starts as false
\def\cp{% comma or period
\ifcomma{,}\else.\fi
}
\def\PI{3\cp14159}
The number $\PI$ is an approximation to $\pi$.
\commatrue
The number $\PI$ is an approximation to $\pi$.
\bye
If you're using LaTeX, there are a few options available; the best is using siunitx and its \num command that will typeset its argument according to what options you have selected.
Use siunitx:
\documentclass{article}
\usepackage[output-decimal-marker={.}]{siunitx}
\begin{document}
you can even use comma \num{123,45} or dot \num{123.45}
\end{document}
just change {.} to {,}. You might also want to use group-separator={.} when using output-decimal-marker={,}. The default group-separator is a thin whitespace.
siunitxalready offers a much better alternative to type-setting numbers. – Qrrbrbirlbel Sep 18 '13 at 12:55.but the output use a comma or both input and output to change or... – David Carlisle Sep 18 '13 at 12:58