When I give matplotlib a annotation string such as

$\frac{A}{B} = C$

and I specify a fontsize of 18, the A and B are rendered at 12.6 pt, while the C is rendered at 18 pt. I want A, B, and C to all be the same size.

In a LaTeX document, if you give the commands

\begin{equation}\frac{A}{B} = C\end{equation}

you get a fraction, where A, B, and C are all the same size, but if you do

$\frac{A}{B} = C$

inline with text, you get the A and B rendered at 12.6 pt, while the C is rendered at 18 pt. Thus it appears matplotlib's mathtext is emulating LaTeX's inline mode. In LaTeX you can write

$\displaystyle\frac{A}{B} = C$

and then A, B, and C are all the same size, even in inline mode. I tried this in matplotlib, but mathtext did not recognize the command \displaystyle. =(

I am aware I can use \displaystyle if I change text.usetex to true in my .matplotlibrc file, but I would like to stay with mathtext since it is a lot faster. Is there a chance of implementing \displaystyle in math text? If not, does anyone have a work around?

My setup: matplotlib v1.2.0, python 2.7, OS X 10.8.3