[Tex/LaTex] Problems with \sum lower limit when in an exponent (displayed maths)

Question

I just can't get the lower limit to be under the $\Sigma $ in an equation that has this:

\begin{align*}
 e^{ - \sum_{x_n \leq t}{g(x_n)} 
\end{align*}

I've tried \[ \] ,the align* environment; and nothing…

Answer 1

Do you mean this? The sum in the exponent looks a little bit too much, but perphaps this is necessary this way.

\limits is meant for providing the limits for a \sum, \int or \prod operator, having the syntax \sum\limits_{lower}^{upper}

\documentclass{article}

\usepackage{mathtools}
\begin{document}

\begin{align*}
 e^{ - \sum\limits_{x_n \leq t}g(x_n)}
\end{align*}
\end{document}