emphasissubscripts
How would I go about adding a subscript to a symbol I'm defining from an equation.
For example I have an equation
E_m = \alpha_m x + y
How can I then do something like \emph \alpha\textsubscript{m}
The above gives me errors and I can't figure out how to correct this.
The slight difference is in the fact that TeX uses "cramped display style" when typesetting the argument to \widehat, which is characterized by reduced lowering of subscripts and raising of superscripts.
This is one of the cases where TeX needs help; here's a way:
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\[
\cramped{\mathbf{L}_\mathbf{s}}
\widehat{\mathbf{L}_\mathbf{s}^{+}}
\]
\end{document}
Alternatively, don't let the wide hat cover also the superscript and subscript:
\documentclass{article}
\begin{document}
\[
\mathbf{L}^{}_\mathbf{s}
\widehat{\mathbf{L}}_\mathbf{s}^{+}
\]
\end{document}
Notice the empty superscript.
Put the \displaystyle in front of the \sums.
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
\Phi(H) = \min \frac{\displaystyle\sum_{\substack{i \in S \\ j \notin S}} w_{ij}}
{\displaystyle\sum_{\substack{i \in S}} \pi_i}
\]
\end{document}
I recommend to put the sums into one line:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
\Phi(H) = \min \bigg(\sum_{\substack{i \in S \\ j \notin S}} w_{ij} \Big/
\sum_{\substack{i \in S}} \pi_i\bigg)
\]
\end{document}
Best Answer
Math formulas should be written in "math mode":
is the correct way to input that formula.
The "Not so short introduction to LaTeX" covers this topic and is available in many languages.