[texhax] \binom

[Rolf Turner]

On 2/03/2009, at 10:47 AM, P. R. Stanley wrote:

> An excellent answer! That's exactly the sort of info I'm after!
> Cheers,
> Paul
>
>> Hi
>>> What does it do? What do you get when you compile $\binom{3}{4}$  
>>> in a
>>> document? Thanks
>>> Paul
>>
>> It sets a 3 above a 4 and encloses them both in a single pair of  
>> sufficiently
>> tall parentheses. The 3 and the 4 are the same size as each other.  
>> You
>> probably already know what it denotes, but just in case you don't,  
>> here's one
>> way to describe it: $\binom{n}{r}$ denotes the coefficient of $x^r
>> y^{n-r}$ in
>> the expansion of $(x + y)^n$.

There's a wee problem in that \binom{3}{4} would denote the  
coefficient of
x^4 y^{-1} in the expansion of (x + y)^3 --- and there isn't one.

As far as I can discern there is no way to make \binom{3}{4}  
meaningful, since
Gamma(0) is undefined.

Now \binom{4}{3} --- that's a different story! :-)

	cheers,

		Rolf Turner

######################################################################
Attention: 
This e-mail message is privileged and confidential. If you are not the 
intended recipient please delete the message and notify the sender. 
Any views or opinions presented are solely those of the author.

This e-mail has been scanned and cleared by MailMarshal 
www.marshalsoftware.com
######################################################################