# Space after comma in empheq package

My MWE,

\documentclass[a4paper,11pt]{book}
\usepackage{empheq}
\begin{document}
0,5
\begin{empheq}{align}
0,5
\end{empheq}
\end{document}


Good (normal) is comma in first 0,5 .

But not good in {empheq} package 0,5 . It have a little space. I want to delete space.

I didn't find duplicate another question. So, does anyone know how to fix it?

Related to: Space after comma in units package

• Use 0{,}5..... – user11232 Nov 28 '14 at 0:07
• A workaround is 0{,}5. The comma always inserts a small space because of the other uses, like (a,b), or \{0,1,2,3\}. In any case, I would choose to write 0.5 and then change the output later. Here is an option. – Manuel Nov 28 '14 at 0:07
• This has nothing to do with empheq; in math mode, the comma is classified as punctuation, so TeX automatically adds a thin space after it. – egreg Nov 28 '14 at 0:09

This has nothing to do specifically with empheq. The simple document

\documentclass{article}
\begin{document}
0,5 $0,5$
\end{document}


will show the same behavior. In math mode a comma is a punctuation symbol, so TeX automatically adds a thin space after it, which is needed in formulas like $(a,b)$.

Either you use 0{,}5 in math mode, because this makes the comma into an ordinary symbol or use a dedicated package such as siunitx.

\documentclass{article}
\usepackage{siunitx}

\sisetup{output-decimal-marker={,}}

\begin{document}
\num{0,5} or \num{0.5} % text mode

$\num{0,5}$ or $\num{0.5}$ % math mode
\end{document}


As you can see, the output is independent of whether you use a period or a comma in the input.

You can reduce the space by putting comma inside braces like 0{,}5. But it is better to use siunitx.

\documentclass[a4paper,11pt]{book}
\usepackage{empheq}
\usepackage[detect-all]{siunitx}
\begin{document}
0,5
\begin{empheq}{align}
0{,}5\\
\num[output-decimal-marker = {,}]{0.5}
\end{empheq}
\end{document}


• Harish Kumar, I wrote about 60 pages. Approximately 600 commas. Is it macro possible, commas only in empheq equation. x,y --> x{,}y Because I don't working your with siunitx package. – Özgür Nov 28 '14 at 2:15