I stumbled upon those two ways of writing a mathematical expression inside a text:
I could easily do the first one by writing the expression inside $s, but what about the second one? If I use \begin{displaymath}, it looks like this:
What is the correct command for this?
Actually there's a third way:
\documentclass{article}
\setlength{\textwidth}{.8\textwidth} % just for the example
\begin{document}
Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny. Ala ma kota
$e=\lim_{n\to\infty}(1+\frac{1}{n})^n=\sum_{n=0}^{\infty}\frac{1}{n!}$ i kot
jest czarny. Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny.
Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny. Ala ma kota
$e=\lim\limits_{n\to\infty}(1+\frac{1}{n})^n=\sum\limits_{n=0}^{\infty}\frac{1}{n!}$ i kot
jest czarny. Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny.
Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny. Ala ma kota
$\displaystyle e=\lim_{n\to\infty}(1+\frac{1}{n})^n=\sum_{n=0}^{\infty}\frac{1}{n!}$ i kot
jest czarny. Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny.
\end{document}
Which one to prefer? The third way is definitely to avoid, because it creates too much space between lines; also the second way has the same defect, but less evident. The first way ensures constant advancement between baselines, making for a better appearance and better readability.
Setting limits to the right, rather than above and below is a device very commonly used in mathematical typography exactly for avoiding the problem of getting bad white stripes in a page. The \limits trick can be handy in some cases, but should not be abused. Using \displaystyle is definitely the wrong way to go.
However, when a formula is rather complex, you should consider setting it in a display, which avoids the problem and makes the formula to stand out.
\documentclass{article}
\setlength{\textwidth}{.8\textwidth} % just for the example
\begin{document}
Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny. Ala ma kota
\[
e=\lim_{n\to\infty}\Bigl(1+\frac{1}{n}\Bigr)^{\!n}=\sum_{n=0}^{\infty}\frac{1}{n!}
\]
i kot jest czarny. Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny.
\end{document}
\displaystyle switches between those two math styles, producing the effect you're looking for.
\documentclass{article}
\begin{document}
Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny.
Ala ma kota $\displaystyle e = \lim_{n\to\infty} (1 + \frac{1}{n})^n
= \sum_{n=0}^\infty \frac{1}{n!}$ i kot jest czarny.
Ala ma kota i kot jest czarny. Ala ma kota i kot jest czarny.
\end{document}
Here's the output:
\displaystyle is just a switch, not a command that takes an argument. In fact, the braces makes things worse, as they prevent linebreaks from occurring.
– Torbjørn T.
Dec 25 '15 at 22:41
\displaystyle, which leads to inconsistent line spacing. There probably will be an answer be @egreg in a few minutes. – Johannes_B Dec 25 '15 at 16:52