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Is there a way to force individual equations to place their equation numbers (or more specifically the result of a \tag*{blah}) on a specific side of the page regardless of the options to amsart.

I sometimes wish to use the equation enviornment to define 'requirements' in my papers which should look like:

R_e: equation stuff

Where R_e is the equation tag. R_e should be on the left even when reqno is passed to the documentclass. How can I accomplish this?

1 Answer 1

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If you just want to do this for the equation environment, define a command to be used in the equation environment:

\newcommand{\LeftEqNo}{\let\veqno\@@leqno}

For instance,

\documentclass{article}
\usepackage{amsmath}
\makeatletter
\newcommand{\LeftEqNo}{\let\veqno\@@leqno}
\makeatother
\begin{document}
  \begin{equation}
    x^2 + y^2 = 1,
  \end{equation}
  \begin{equation}\LeftEqNo
    x^2 + y^2 = 1.
  \end{equation}
\end{document}

The align environment is implemented quite differently, and you will need the environ package used like

\usepackage{environ}
\makeatletter
\NewEnviron{Lalign}{\tagsleft@true\begin{align}\BODY\end{align}}
\makeatother

Then use \begin{Lalign} ... \end{Lalign} for left-numbered align environments.

I'm afraid that various hacks of the same kind will be necessary for the other ams environments, but I can't list everything without knowing which ones you need :).

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  • equation or possibly align is fine. I plan to wrap this in a special environment for this construct and it will be one of those two. Commented Jan 2, 2011 at 0:18
  • When I try this (using pdflatex) I get an error: ! Undefined control sequence. \env@Lalign@process ->\tagsleft
    – Sam Nead
    Commented Sep 9, 2011 at 14:59
  • @Sam Nead: I assume you might have a different version of the environ package. Can you post somewhere the result of \listfiles? Commented Sep 11, 2011 at 17:17
  • Using the command \LeftEqNo in equation as above, LaTeX reports the error "ERROR: You can't use `\spacefactor' in display math mode." and "\veqno ->\spacefactor \@m l.1567 \end{equation}". What is wrong?
    – gofvonx
    Commented Feb 6, 2014 at 10:16
  • 1
    @gofvonx I've updated with a full example. I had forgotten to mention the need for \makeatletter and \makeother when one works with commands whose name contains @. Commented Feb 7, 2014 at 22:32

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