I am working on a formulae in a notes. Here is part of my code,
\begin{equation*}
\phi(x) := \left\{
\begin{aligned}
&\chi_{K_n}(\bar{x})\cdot\frac{\psi_n(x)}{\tilde{\psi}_n(\bar{x})}, & \text{ if } \bar{x}\in K_n \\
&0 & \text{ otherwise}
\end{aligned}
\right.
\end{equation*}
The problem is that I need a subcript of a subscript in \chi_{K_n}, but \chi is a small letter, K is a capital letter. With a small subscript n on the right, it looks like \chi times K_n, is there a way to make \chi bigger or make the subscript K smaller? Thanks.
By the way, can I post math formulae here like I do in mathstakexchange?
\chi^{}_{K_{n}}
, which will move the subscript down. – egreg Apr 28 '15 at 13:46