[R] BUG: choose function

[Benilton Carvalho]

Thanks for the clarifcation, Duncan.

Best,

B

On Nov 22, 2007, at 8:32 PM, Duncan Murdoch <murdoch at stats.uwo.ca>  
wrote:

> On 22/11/2007 8:11 PM, Benilton Carvalho wrote:
>> well,
>> choose(n, k) should actually return:
>> factorial(n)/(factorial(n-k)*factorial(k))
>
> That's not how the docs define it.  They say
>
> Note that 'choose(n,k)' is defined for all
>     real numbers n and integer k.  For k >= 1 as n(n-1)...(n-k+1) /
>     k!, as 1 for k = 0 and as 0 for negative k.
>
> which agrees with your definition only for 0 <= k <= n.
>
> Duncan Murdoch
>
>> R-2.6.0 works just fine for me.... so does R-2.5.1.... so does   
>> R-2.4.1....
>> b
>> On Nov 22, 2007, at 8:04 PM, Luis Salasar wrote:
>>> Hi,
>>>
>>> I have used the function choose(n, k) sometimes, and i realized   
>>> that it doesn't work properly for n < 0. For example, if one  
>>> tries  choose(-1, 3), it should be returned the value (-1)^3 = -1,  
>>> since  choose (-1, 3) = (-1)*(-2)*(-3)/3! = (-1)^3, but indeed R  
>>> returns  the value 0. I am using R version 2.5.1, it don't know if  
>>> this  little bug has already been solved in the new version. Thanks,
>>>
>>> Luis Ernesto.
>>>
>>>
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