# Comma as decimal point leading to confusion [duplicate]

I'm writing a report in a language that uses decimal commas. In some cases that clashes with commas used for punctuation, causing hard to read text, e.g.:

for $x_i \in [-1,5, 1,5]$.

Is there a way to make this more readable?

• Jul 26 '11 at 17:51
• Of course you aren't writing $ and $ for the brackets, are you? Jul 26 '11 at 17:54
• @egreg: Oops, no I'm not. Jul 26 '11 at 17:58

If you're using the comma as decimal separator, then you should consider using the semi-colon for the interval separator, it will be more readable:

$x_i\in[-1{,}5;1{,}5]$


(Instead of typing 1{,}5, you can also use the icomma package as suggested by egreg or \num as suggested by Werner.)

• That was the first version I tried. Looks good on the screen but I didn't like it very much when printed. Jul 26 '11 at 18:12
• +1, semicolon should absolutely be used. Spacing is nice and all but even with proper spacing this is way too confusing otherwise. Jul 26 '11 at 18:52
• @htorque: in French you would also add a thin space \, before the semi-colon. To my eye, it improves even further the readability of the formula, but depending on the language you're using, it might be against the rules. Jul 26 '11 at 19:04
• +1 also from me. A semicolon should be used indeed. Dec 25 '12 at 15:59
\usepackage{icomma}
...
for $x_{i}\in[-1,5, 1,5]$.


Notice the space after the comma where you want it to act as a punctuation symbol.

• Nice, definitely an improvement! Yet I think it still needs additional space between the elements (like suggested by Stephen). Jul 26 '11 at 18:11
• Trying this in 2020: this package should be installed from "was": tlmgr install was May 22 '20 at 17:34

The siunitx package provides a general way of treating numbers and their decimal symbols. However, you have to explicitly encompass the numbers with \num{...}. For example:

\documentclass{article}

\usepackage[output-decimal-marker={,}]{siunitx}

\begin{document}

This is a range $x_i \in [\num{-1.5}, \num{1.5}]$.% ...or [\num{-1,5}, \num{1,5}]

\end{document}​​​​​​​​​​​​​​​​​​


would produce

• This has been replaced by output-decimal-marker in siunitx version 2. Jul 27 '13 at 20:31
• And in 2021 (but it has been that way for a while, I just don't know since when) you don't have to use the comma inside the \num{}: you can just use the point and change output-decimal-marker depending on the language you want to compile your document for. Oct 21 at 5:27

You could try \; or \, or ~ as space (instead of " "):

$x_i \in [-1,5,\;1\,1~1,5]$


and use a semicolon for the interval separator (as already suggested by Philippe Goutet).