[Tex/LaTex] Fix ugly kerning in equation subscript

Question

I'm beautifying some HW solutions for the upcoming semester, and came across a kerning issue

\documentclass[]{article}
\usepackage{amsmath}
\begin{document}
\[C_{in} \ \ C_{out} \ \ C_{eff}\]

\end{document}

The output:

The "in" and "out" subscripts look fine, but "eff" seems very spread out. Is there a quick fix?

Answer 1

In math-mode you should to use \mathit{...} (slanted} or \mathbf{...} (bold) or normal \mathrm{...} for any type of the text into math formula.

\documentclass{article}
\begin{document}
\[C_{\mathit{in}} \ \ C_{\mathit{out}} \ \ C_{\mathit{eff}}\]
\[C_{\mathrm{in}} \ \ C_{\mathrm{out}} \ \ C_{\mathrm{eff}}\]
\[C_{\mathbf{in}} \ \ C_{\mathbf{out}} \ \ C_{\mathbf{eff}}\]
\end{document}