Prevent automatic resizing of equation elements

Question

I have the following equation:

\begin{equation}
E(W) = \frac{\frac{(c\rho)^c}{c!}}{(1-\rho)\sum_{n=0}^{c-1}(\frac{(c\rho)^n}{n!})+\frac{(c\rho)^c}{c!}} \cdot \frac{1}{1-\rho} \cdot \frac{1}{c\mu}
\end{equation}

which is rendered as

Is there any easy way to prevent that the nominator and denominator of the main fraction to be each displayed in inline math mode? E.g. I want my summation to look like this instead of the way it looks right now.

but as far as I understand this the equation is already in display math, or is there a way to force display math for the individual elements of the equation aswell? — charelf, Nov 30 '20 at 21:12
add \limits directly after the \sum command \sum\limits_{n=0}^{c-1} ... — Alan Munn, Nov 30 '20 at 21:15
Sebastiano meant \frac{\displaymath ...}{\displaymath ...} so numerator and denominator are set in display style — David Carlisle, Nov 30 '20 at 21:16
@DavidCarlisle Thank you so much for your help in English and for the explanation. :-) — Sebastiano, Nov 30 '20 at 21:20

score 2 · Accepted Answer · answered Nov 30 '20 at 21:24

Here there is my version using also \displaystyle and \dfrac. I not very good for the explanations :-).

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath,amssymb}
\begin{document}
\begin{equation}
E(W) = \frac{\dfrac{(c\rho)^c}{c!}}{(1-\rho)\displaystyle\sum_{n=0}^{c-1}\left(\frac{(c\rho)^n}{n!}\right)+\frac{(c\rho)^c}{c!}} \cdot \frac{1}{1-\rho} \cdot \frac{1}{c\mu}
\end{equation}
\end{document}

However you can see also this link: equal size numerator and denominator

Prevent automatic resizing of equation elements

1 Answers1