Problem with \sum subscript

Question

When I use the code below the subscript j appears to the side of the sum symbol, not underneath. Has anyone got any idea what I'm doing wrong?

\begin{equation}
    \Delta{t}\leq\left[{C_i}\over{{\sum_{j}}{\frac{1}{R_{ij}}}}\right]_{min}
    \label{eq:stability_criteria_3}
\end{equation}

Please put your code in Code Samples (the '{}'-button) to make it more readable — Didii, Jul 23 '12 at 13:56
Here is the same issue in another environment. Solution is the same: http://tex.stackexchange.com/questions/3262/big-sum-instead-of-small-sum-in-array-environment — Didii, Jul 23 '12 at 14:03
In LaTeX, rather use \frac{<num>}{<denom>} than <num>\over<denom>. — Werner, Jul 23 '12 at 14:18

score 8 · Answer 1 · edited Jul 23 '12 at 14:38

8

Adding a \displaystyle does the job.

\begin{equation} \Delta{t}\leq\left[{C_i}\over{{\displaystyle \sum_{j}}{\frac{1}{R_{ij}}}}\right]_{min} \label{eq:stability_criteria_3} \end{equation}

edited Jul 23 '12 at 14:38

doncherry

54,637

answered Jul 23 '12 at 14:04

Corentin

9,981

The \displaystyle instruction will change both the size of the summation symbol and the default placement of the limit(s) of summation. – Mico Dec 20 '12 at 13:24

score 5 · Accepted Answer · answered Jul 23 '12 at 14:03

5

Consider using \limits as in the following:

    \begin{equation}
\Delta{t}\leq\left[{C_i}\over{{\sum \limits_{j}}{\frac{1}{R_{ij}}}}\right]_{min}
\label{eq:stability_criteria_3}
     \end{equation}

(Doesn't this make this ugly though?)

answered Jul 23 '12 at 14:03

kan

4,545

Problem with \sum subscript

2 Answers2

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