On Thu, Dec 17, 2009 at 03:10:49PM +0100, Martin Maechler wrote:
[...]
> MM> This, of course, is an even more compelling reason to implement
> MM> the change of return log(abs(choose(.,.)),
> MM> and at the moment, I'd even plan to "backport" that to R "2.10.1
> MM> patched", as th
> "MM" == Martin Maechler
> on Tue, 15 Dec 2009 14:54:18 +0100 writes:
> "PS" == Petr Savicky
> on Tue, 15 Dec 2009 10:52:43 +0100 writes:
PS> On Tue, Dec 15, 2009 at 09:49:28AM +0100, Martin Maechler wrote:
>>> lgamma(x) and lfactorial(x) are defined to return
> "PS" == Petr Savicky
> on Tue, 15 Dec 2009 10:52:43 +0100 writes:
PS> On Tue, Dec 15, 2009 at 09:49:28AM +0100, Martin Maechler wrote:
>> lgamma(x) and lfactorial(x) are defined to return
>>
>> ln|Gamma(x)| {= log(abs(gamma(x)))} or ln|Gamma(x+1)| respectively.
Martin Becker wrote:
Robin Hankin wrote:
...
Is this the place to discuss having complex
arguments for gamma()?
...
If this discussion starts I would second the wish for the
functionality of gsl's lngamma_complex in base R.
Do you mean gsl or GSL? ;-)
[the GNU scientific library is 'GSL'
Robin Hankin wrote:
...
Is this the place to discuss having complex
arguments for gamma()?
...
If this discussion starts I would second the wish for the functionality
of gsl's lngamma_complex in base R.
Best wishes
Martin
--
Dr. Martin Becker
Statistics and Econometrics
Saarland University
On Tue, Dec 15, 2009 at 09:49:28AM +0100, Martin Maechler wrote:
> lgamma(x) and lfactorial(x) are defined to return
>
> ln|Gamma(x)| {= log(abs(gamma(x)))} or ln|Gamma(x+1)| respectively.
>
> Unfortunately, we haven't chosen the analogous definition for
> lchoose().
>
> So, currently
>
>
Hi Martin
I think you're absolutely right about this;
One thing I need again and again is
a multinomial function, and usually define:
> lmultinomial
function (x)
{
lfactorial(sum(x)) - sum(lfactorial(x))
}
> multinomial
function (x)
{
exp(lmultinomial(x))
}
It would be nice to have this
lgamma(x) and lfactorial(x) are defined to return
ln|Gamma(x)| {= log(abs(gamma(x)))} or ln|Gamma(x+1)| respectively.
Unfortunately, we haven't chosen the analogous definition for
lchoose().
So, currently
> lchoose(1/2, 1:10)
[1] -0.6931472 -2.0794415NaN -3.2425924NaN
