Open nbeisert opened 4 years ago
Just a quick comment: if you only want to number one equation in an align block, might one alternative idea here be to use the following instead?
\begin{align}\begin{split}…\end{split}\end{align}
In that case the additional options could be added to the split environment to control where its number is placed (first/last/middle, etc.).
@wspr: thanks for the suggestion, but that one does not break across pages on \allowdisplaybreaks
(by design).
This issue has been automatically marked as stale because it has not had recent activity.
Brief outline of the bug
The
align
environment for equation blocks inamsmath
(and similar environments) number all lines with equation numbers. The numbering can be suppressed for individual lines (\nonumber
,\notag
) or for all lines (align*
). However, it is tedious and error-prone to just number few, selected lines. For instance, it may be desirable to only assign a number to the first or the last (or a user-selected) equation within each block, and to do that consistently throughout the document. While certainly possible with existing commands, it requires many\nonumber
insertions at the right places.I would like to suggest an extension to the equation numbering mechanism in
amsmath
to:The below example contains suggested patches for
amsmath
to implement the suggested extensions.Minimal example showing the bug
Some remarks
\donumber
activates the number on an otherwise unnumbered line.align
,gather
,multline
andequation
; for the latter two environments, their single equation number is merely removed in mode b) (no numbering); this is for a consistent uniform behaviour of all math environments.\numberhere
selects the present line to carry the main equation number for the block (in case the first, last line are too long).\eqnumbering@
controls the mode; a suitable interface would be required to select the mode; this could be achieved by package option or a dedicated selection command.\scheme
can be used to test different situations.PDF and log files
amsmathnum.log amsmathnum.pdf