[Tex/LaTex] Making the subscript under the summation

math-modesubscripts

I'm writing some formulas inside a tabular. My formulas have summation but the subscript is showing next to the summation not under it! How can I make it under it?

Example (j is next to summation!):

enter image description here

Best Answer

You can force the subscripts to be under the summation, by using \limits, like this:

\sum\limits_{j=1} A_{xj}

An alternative way is to change the typesetting style of the formula by using \displaystyle. You probably already noticed, that the typesetting of math differs depending on what 'mode' your in: inline math or display math:

\documentclass[10pt,a4paper]{article}
\usepackage{amsmath}
\begin{document}
This sum $\sum_{i=1}^{\infty} \frac{1}{i}  $ looks different than
\[
    \sum_{i=1}^{\infty} \frac{1}{i}
\]
\end{document} 

Output:

enter image description here