numerical evaluation of quotients of gamma functions
Subject: numerical evaluation of quotients of gamma functions
From: Kris Katterjohn
Date: Fri, 01 Nov 2013 18:58:31 -0500
On 11/01/2013 06:36 PM, Raymond Toy wrote:
>>>>>> "Barton" == Barton Willis <willisb at unk.edu> writes:
>
> Barton> Yes that's also a good idea. But I think I'd need to write
> Barton> my own log-base-two-gamma-function? Or am I missing
> Barton> something?
>
> Oh, you wanted something that was already built in? Then I don't
> really know, other than doing log(gamma(x)), which might be good
> enough for now if gamma(x) doesn't overflow and you don't care about
> the precision loss in log(gamma(x)). I guess that's at most 10 bits of
> precision lost.
>
> But we might consider providing a loggamma function since it's so easy
> for gamma to overflow a double float. This doesn't help you solve your
> problem though.
>
Maxima already has the logarithm of the gamma function as log_gamma.
> Ray
>
Cheers,
Kris Katterjohn