# Subequation behavior for ungrouped equations?

I have several equations at different places in my paper, and I want to number them as I would using subequations, e.g. 1.a, 1.b, 1.c, 1.d. The problem is that they do not follow each other immediately and as I understand it, that prevents me from using the subequations environment. Is there a way around it?

If the subequations occur in sequence, i.e., if there's no equation numbered (say) "2" between equations numbered "1b" and "1c", there's no problem having text and equations interspersed within the part of the document that's set off by the \begin{subequations} and \end{subequations} statements.

The following example, for instance, produces four equations numbered "1a" through "1d" even though there are entire paragraphs between some of the equations.

(Aside: If your document contains chapter divisions, you won't let the subequations environments straddle \chapter directives, right?)

\documentclass{article}
\usepackage{amsmath}  % for "subequations" and "gather" environments
\usepackage{lipsum}   % for filler text
\begin{document}
\begin{subequations}
\lipsum[1]
$$1+1=2$$  % equation "1a"
\lipsum[2]
\begin{gather} 2+2=4 \\ 3+3=6 \end{gather} % equations "1b" and "1c"
\lipsum[3]
$$4+4=8$$  % equation "1d"
\end{subequations}
\end{document}