# Testing whether a document has option "fleqn"

Hefferon, Jim S. jhefferon at smcvt.edu
Sat May 4 00:30:49 CEST 2019

How can I test whether the document has the class option fleqn?  I want to have an environment that takes the place of center but that if required gives content that is left-aligned, as equations are left-aligned under fleqn.

I had in mind something like this.  However this one gives ! LaTeX Error: Can be used only in preamble.

\newenvironment{display}{%
\@ifclasswith{fleqn}{
\trivlist \item \relax \hspace*{\mathindent}
}{
\trivlist \centering \item \relax
}}{
\endtrivlist
}

I know that there are flags like \@fleqntrue and have spent some time trying toggle commands, etc, but been unable to hit on the right one.  A tip would really help me.

Thank you,
Jim

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