Hi Colin,
here I just change to the text font size of 11pt, you will see that is works for 11pt too:
Code: Select all
\documentclass[12pt,letterpaper]{report}
\DeclareMathSizes{11}{55}{15}{15}
%\DeclareMathSizes{12}{55}{15}{15}
\begin{document}
\fontsize{11pt}{13.6pt}\selectfont
Hello this is regular text. This should be really big: $a=5$
\end{document}
As \small corresponds to \@xipt, that's equal to 10.95pt, not to 11pt, try this:
Code: Select all
\documentclass[12pt,letterpaper]{report}
\DeclareMathSizes{10.95}{55}{15}{15}
%\DeclareMathSizes{12}{55}{15}{15}
\begin{document}
\small
Hello this is regular text. This should be really big: $a=5$
\end{document}
Similar if you switch to the 11pt option for report:
Code: Select all
\documentclass[11pt,letterpaper]{report}
\DeclareMathSizes{10.95}{55}{15}{15}
\begin{document}
Hello this is regular text. This should be really big: $a=5$
\end{document}
Stfan