Math & Science ⇒ \sum in fractions problem

[stuartjcsmith]

I want to place a "sum of" sign (\sum) within a fraction but I don't like the way that it appears when compiled i.e. the N above it and the i = 1 below it appear as plain superscripts and subscripts respectively but I want them to be directly above and below the "sum of" sign on the top and bottom of the fraction. Normally, if you use \displaymath, then this works fine but I need the equation to be correctly numbered so I need to use it within the \equation environment. Here is an example of the code I am using:

Code: Select all

\begin{equation}
x = \frac{\sum{i}^{N}_{i = 1}}{\sum{j}^{N}_{j = 1}}
\end{equation}

Please help, is there a package or something that I can use to correct this?

[localghost]

First of all you have the wrong sequence in your equation. Right after the summation sign (Sigma) there have to follow the limits. These limits can be aligned as desired with a supplement.

Code: Select all

\begin{equation}
  x=\frac{\sum\limits^{N}_{i=1}i}{\sum\limits^{N}_{j=1}j}
\end{equation}

Alternatively you can switch to display style separately in the numerator and denominator of the fraction. The summation sign then will appear bigger. More useful hints about typesetting mathematical expressions can be found in the "Math mode" document.


Best regards and welcome to the board
Thorsten¹

[stuartjcsmith]

Thank you for the help!
It works.

Thanks for the welcome too. Bye.