Using mathjax is very useful for rendering equations. However getting things to work as expected can be challenging
Different renderers can been diifferent approaches. Does single dollar sign $\left \langle C \right \rangle _{m = i} = \frac{1}{z}\sum_j^z C_j P(C_j \mid m = i)$
Or do you need to use double dollar sign \(\left \langle C \right \rangle _{m = i} = \frac{1}{z}\sum_j^z C_j P(C_j \mid m = i)\).
If we can render this sucessfully we can continue to create interesting websites using convenient markdown.