4

I want to post something on math.stackexchange, but I have doubts about visual aspects of it. Take a look at

$ {n \choose \lfloor \frac{n}{2}\rfloor} $

or

$ { {n} \choose \frac{n}{k}} $

It just doesn't look good. The "n" and "k" inside {n \choose k} that I use here are too close to each other (and a little disproportional). Can something be done with this? Or I must to manually invent something similar to {n \choose k} with brackets or other things?

Thank you for any advice :-)

Edit:\ By "n" and "k" I don't literally mean the n,k, but the phrases they represent, the upper and lower component of {n \choose k}

  • 4
    Does \binom{n}{k} behave better? – Torbjørn T. Mar 27 '14 at 7:48
  • 1
    Avoid fractions inside (generalized) fractions: \binom{n}{\lfloor n/2\rfloor} will typeset just right. – egreg Mar 27 '14 at 7:51
  • > TorbjørnT. Unfortunately it looks almost the same. > egreg, Thanks, since it is only n/k, I think I will do this way if I don't find other solution, but there can be examples more complicated than this, that could "look better" by just 'separating' them up-down a little. Even if my question above is limited to MathJax used by math.stackexchange, I am also curious if we can do something with this in "normal" LaTeX. There must be some people, who had similar "problems" while writing some mathematical papers, thus they sought for solution, mustn't there? :-) – Kusavil Mar 27 '14 at 8:12
  • Or maybe this is just problem with latex at math.stackexchange site? Does \binom{n}{k} works good in normal latex? (I have new laptop and still didn't installed proper environment for LaTeX, thus I won't check it now). – Kusavil Mar 27 '14 at 8:29
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    @Kusavil Yes, \binom works well. MathJax is not LaTeX, and its rendering is usually rather poor, when complex structures such as fractions, radicals and matrices are involved; the weakest point are the delimiters. – egreg Mar 27 '14 at 8:42
7

Here's a comparison; note that you should always avoid fractions in one of the arguments to \binom (which is preferred over the infix \choose).

\documentclass{article}
\usepackage{amsmath}

\begin{document}
Bad

Text style: $\binom{n}{\lfloor \frac{n}{2}\rfloor}$

Display: $\displaystyle\binom{n}{\lfloor \frac{n}{2}\rfloor}$

Good

Text style: $\binom{n}{\lfloor n/2\rfloor}$

Display: $\displaystyle\binom{n}{\lfloor n/2\rfloor}$
\end{document}

enter image description here

You can immediately see that the two story fraction is wrong.

Here's the rendering by MathJax of the same input (at least, what I get on my machine):

enter image description here

  • Thank You again, I read something about MathJax just now and didn't realized the real nature of problem before posting here. Thus, I will just use n/2 instead \frac{n}{2}. – Kusavil Mar 27 '14 at 8:58

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