matplotlib mathtext \frac is too small

Question

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. How do I do this?

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. =(

Is there a way to get this to work in Matplotlib's mathtext, or am I stuck changing text.usetex to true in my .matplotlibrc file? (If possible I would like to stay with mathtext since it is a lot faster.)

My setup: matplotlib v1.2.0 python 2.7 OS X 10.8

Answer 1

For anyone stumbling on this and also not wanting to set "text.usetex" to True, matplotlib now supports the \dfrac macro (equivalent to \displaystyle\frac in LaTeX) to replace \frac since version 2.1

Answer 2

As you said, you can fix it by using \displaystyle:

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

In order to allow matplotlib to use latex for all text handling you have to define in your matplotlibrc the text.usetex variable as True:

text.usetex          : True

I made a little example to verify it and it is working well:

import matplotlib.pyplot as plt
plt.plot(range(200))
plt.text(100,50,r'$\displaystyle\frac{A}{B}=C$')

I am sorry but since I am new, I can not post any image.