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I have an equation contained inside \[...\], which automatically makes a \sum with sub- and superscripts turn big--so that the summation sign looks awkward inside parenthesis. Any idea how to make the parenthesis completely enclose the whole summation?
\documentclass{article}
\begin{document}
We have:
\[ \sum_{i=1}^n i = (\sum_{i=1}^{n-1} i) + n =
\frac{(n-1)(n)}{2} + n = \frac{n(n+1)}{2} \]
\end{document}
The usual thing to do is replace ( with \left( and ) with \right), which automatically expand to fit the material between them. Note that every \left... requires a \right... (but the type of bracket may be different, i.e. \left(...\right] also works).
I would typeset your equation as
\begin{equation*}
\sum_{i=1}^n i = \left(\sum_{i=1}^{n-1} i\right) + n =
\frac{(n-1)(n)}{2} + n = \frac{n(n+1)}{2}
\end{equation*}
For manual control of sizes (most of the time you won't need these)
( \big( \Big( \bigg( \Bigg(
produce
amsmath defines \[...\] to be exactly the same as \begin{equation*}...\end{equation*}. See, literally, the last couple of lines of amsmath.sty.
\left[...\right]. These often look better for larger equations. Another thing to take into account is that you're enclosing something relatively thin in those brackets. I suspect it will only look more natural when there's more between them (try putting the n to the left of the sum and loosing the brackets altogether).
\left/right around sums etc. because they often become too large. I tend to recommend users to: Scale the fences (parenteses and such) such that it is clear to the read what they fence in, but not to such an extend that the fences dominate the expression.
\big... family of commands. In fact, I personally believe that most of the times one shouldn't use the \left...\right construct; the family of \big... commands produces much better spacing (both vertically and horizontally) in most situations; besides you don't need to match them across lines in a display.
Apr 12, 2013 at 20:19
Automatically sized parentheses are obtained with \left and \right, as any LaTeX guide or manual tells.
However, automatic sizing is not good in every case; one of these cases is precisely that of summations with limits above and below: compare the results of
\[
\left( \sum_{i=1}^{n-1} i \right)\biggl(\sum_{i=1}^{n-1} i\biggr)
\]
(the font is that obtained with \usepackage{fouriernc}). In general the second way is to be preferred.
File fouriernc.sty' not found.` and it looks like just including the package is not enough. This file has to beinstalled manually.
One way is using \left and \right, followed by the parenthesis you want to use. These are mostly () [] {} \langle\rangle and |. You can also use a . to have no parenthesis displayed, e.g. when you want an opening, but no closing one.
\left( \frac12 \right)
\quad
\left\langle \frac23 \right.
\quad
\left\{ \frac34 \right]
creates
If you want to control the size manually, use (in ascending order) \big, \Big, \bigg, \Bigg.
( \frac12 \big)
\quad
\Bigg\langle \frac23 \big]
\quad
\Big\{ \frac34 \Bigg.
results in
\bigl in front of the left delimiter and \bigr in front of the right delimiter (similarly for \Bigl-\Bigr and the others). This is important for spacing.
\big and friends? i.e., without the l|r suffix?
\big| is not a part of a pair: \big|-x\big|\neq \bigl|-x\bigr|
{ size by the formula inclosed in it. I used \left{. your answer was great. it learned me to use \left\{ instead
Aug 8, 2015 at 10:19