This defines a “variable” width which has the properties you want. Replace\makeatletter \def\maxwidth{% \ifdim\Gin@nat@width>\linewidth \linewidth \else \Gin@nat@width \fi } \makeatother
\
linewidth
if you have a different constraint on the width
of the graphic.
Use the command as follows:
\includegraphics[width=\maxwidth]{figure}
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