How do I get \DeclareMathOperator to put the limit beneath? [duplicate]

Question

I use at the picture above: \DeclareMathOperator{\vo}{vol}
And this is the complete line:

\[
\lim_{a}=\vo_{a}
\]

I can make that the a will be below the vol? (like the lim).

Thank you!!

Answer 1

Use the starred version of the command: \DeclareMathOperator*

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator*{\vo}{vol}
\begin{document}
\[
\lim_{a}=\vo_{a}
\]
\end{document}