Math text in matplotlib is rendered smaller than the regular text as show by

ax.set_xlabel(r'Variable $\alpha$')

Further details of this problem are discussed at

https://stackoverflow.com/questions/15836050/matplotlib-change-math-font-size

However the users need variables in math mode of same size as other text.

This should be the default.

I also discuss this problem at

https://stackoverflow.com/questions/41555340/matplotlib-correct-math-font-size