I have had trouble trying to express a sigma sum formula.
Please do not think I have been lazy, I have been lazy, it is just I have up attempting to work it out after over 2 hours (when my actual question still remains to be written).
I was intending to specify a sigma with a variable ( n) at the top right of it And a (i=1) on the bottom right of the sigma. I have made many attempts, but I cannot have an "=" expression instead of a simple variable (like i on its own).
Many thanks
I think you want something like this $$\sum_{i=1}^n a_i$$
This is given by \sum_{i=1}^n a_i.
Formatting tips here.
If you omit the curly braces, then characters will be omitted. For example
Notice the difference when I write \frac123
$$\frac123$$
versus \frac{1}{23}
$$\frac{1}{23}$$.
\sum\limits_{i=1}^{\infty}
$\sum\limits_{i=1}^{\infty}$
if you want a bigger sigma so
\displaystyle\sum\limits_{i=1}^{\infty}
$\displaystyle\sum\limits_{i=1}^{\infty} $
\sum_{i=1}^{\infty} and \displaystyle\sum_{i=1}^{\infty} giving $\sum_{i=1}^{\infty}$ and $\displaystyle\sum_{i=1}^{\infty}$
$\endgroup$
\displaystyle or \limits in inline math. It looks horrible.
$\endgroup$
Commented
Jan 19, 2016 at 11:01
It sounds like your are looking for the code for $\sum_{i=1}^n$, which is $\sum_{i=1}^n$.
The point here is that the command _ which makes the lower index just takes the first character of some larger text unless you put curly brackets around the whole text. The same is true for ^.
