Basically \ang{17.8(3)} simply ignores the uncertainty and forces one to use \qty{17.8(3)}{\degree} instead. It would be useful in context of introductory laboratory courses where we teach measurement and how to propagate uncertainties. While the workaround with \qty exists, I did inadvertently make a lab quiz (my bad) that was easier than intended by creating and printing the quiz on the spot before checking that the angle had an uncertainty!
\listfiles
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{siunitx}
% siunitx prefs
\sisetup{per-mode = symbol} % display units as fractions such as m/s
\sisetup{separate-uncertainty = true} % this prints the uncertainties as \pm and not as bracketed.
%-----------------------------------------------------------------------------
% Document begins
%-----------------------------------------------------------------------------
\begin{document}
\noindent Would be nice if \textsf{siunitx} \verb!\ang! would parse uncertainties the same way as \verb!\qty!
\vspace{2em}
Reference output: \qty{17.8(3)}{\degree} \hfill \verb!\qty{17.8(3)}{\degree}!
\vspace{2em}
\textsf{siunitx} output: \ang{17.8(3)} \hfill \verb!\ang{17.8(3)}!
\vspace{2em}
\noindent (Running MiKTeX, most recent versions of all packages as of May 27th, 2026.)
\end{document}
Minimal.pdf
Minimal.txt
Basically \ang{17.8(3)} simply ignores the uncertainty and forces one to use \qty{17.8(3)}{\degree} instead. It would be useful in context of introductory laboratory courses where we teach measurement and how to propagate uncertainties. While the workaround with \qty exists, I did inadvertently make a lab quiz (my bad) that was easier than intended by creating and printing the quiz on the spot before checking that the angle had an uncertainty!
\listfiles
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{siunitx}
% siunitx prefs
\sisetup{per-mode = symbol} % display units as fractions such as m/s
\sisetup{separate-uncertainty = true} % this prints the uncertainties as \pm and not as bracketed.
%-----------------------------------------------------------------------------
% Document begins
%-----------------------------------------------------------------------------
\begin{document}
\noindent Would be nice if \textsf{siunitx} \verb!\ang! would parse uncertainties the same way as \verb!\qty!
\vspace{2em}
Reference output: \qty{17.8(3)}{\degree} \hfill \verb!\qty{17.8(3)}{\degree}!
\vspace{2em}
\textsf{siunitx} output: \ang{17.8(3)} \hfill \verb!\ang{17.8(3)}!
\vspace{2em}
\noindent (Running MiKTeX, most recent versions of all packages as of May 27th, 2026.)
\end{document}
Minimal.pdf
Minimal.txt