[SciPy-User] the skellam distribution

[Bruce Southey]

On 11/09/2009 12:20 PM, Ernest Adrogué wrote:
>   9/11/09 @ 17:01 (+0100), thus spake Johann Cohen-Tanugi:
>    
>>    From what I understand of the initial statement from Ernest:
>> "
>> In case somebody is interested, or you want to include it
>> in scipy. I used these specs here from the R package:
>> cran.r-project.org/web/packages/skellam/skellam.pdf
>> "
>>
>> he used the spec, as defined in this pdf, and did not look at the code
>> itself. If my interpretation of the small preamble above is correct, I
>> believe his implementation is not GPL-tainted, right?
>>      
> Your interpretation of my preamble is correct.
> I didn't look at the source code, I only read the PDF doc
> where they explain in plain English how the pmf and cdf are
> calculated.
>
>    
Okay,
Then just provide a suitable reference outside the R package where 
someone can derive it independently or get more details. This also 
allows people to go back and check the implementation when things are 
not as expected. Perhaps the reference that Josef provided provides the 
same formulation?

Bruce