Numbering new environment with chapter/section

Question

If I have a new environment defined (with, say, trivfloat), is it possible to get that section to number with chapter/section? I use \numberwithin for equations, figures, and tables.

For example, my equations and figures are numbered 1.1, 1.2, 1.3, 2.1, ... (or even 1.1.1, 1.1.2, ...) But if I have a new float type (say, graph), \numberwithin won't work.

\trivfloat{graph}
\numberwithin{graph}{section} % Error...

Same happens if I use \DeclareCaptionType from the caption package.

Any thoughts on how to get this effect?

Answer 1

The trivfloat package seems to defer (much of) the definition of its new floats using \AtBeginDocument, so you also have to use \AtBeginDocument{\numberwithin{graph}{section}} to change the floats' numbering.

\documentclass{amsart}

\usepackage{trivfloat}

\trivfloat{graph}

\AtBeginDocument{\numberwithin{graph}{section}}

\begin{document}

\section{First}

\begin{graph}[h]
(Graph content)
\caption{A graph}
\end{graph}

\end{document}