# Use of mathtools

I have defined the \absas described in the Mathtools Users Guide 3.6. But I would like to habe the stared-version as default (=\abs). I looked further and found on 3..6.1 (as I thought) a way to do this. But I failed: Changing {star} and {nostar} doesn't make any difference. Am I wrong with my thinking?

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}
% Example from Mathtools-Manual 3.6.1
%\DeclarePairedDelimiter\abs\lvert\rvert
%   \reDeclarePairedDelimiterInnerWrapper{\abs}{star}{#1#2#3}
%   \reDeclarePairedDelimiterInnerWrapper{\abs}{nostar}{\mathinner{#1#2#3}}
% MY try:
\DeclarePairedDelimiter\abs\lvert\rvert
\reDeclarePairedDelimiterInnerWrapper{\abs}{nostar}{#1#2#3}
\reDeclarePairedDelimiterInnerWrapper{\abs}{star}{\mathinner{#1#2#3}}
%
\begin{document}
%
$\abs{\frac{\pi}{2}} \quad \quad \abs*{\frac{\pi}{2}}$
%
\end{document}

• Did you see the posting Swap definition of starred and non-starred command? – Mico Aug 31 '16 at 13:37
• Trust me: you don't want to use automatic sizing by default. – egreg Aug 31 '16 at 13:43
• @ Mico, no, but now. Thanks for the link. @egreg: can you explain this to me? – Ulrich Aug 31 '16 at 14:25
• @Ulrich Most of the times, the automatic sizing chooses too big fences than necessary. – egreg Aug 31 '16 at 14:57
• @egrep: i.e. \abs{x} is ok but \abs*{x} maybe wrong (I guess you have a better example)? So your recommondation is to use use the stared-version only in displayed math environments? – Ulrich Aug 31 '16 at 15:17