digamma function

[Henning Thielemann]

On Sat, 3 Nov 2012, Ben Gamari wrote:

> My digamma package[1] implements an approximation to the digamma
> function (due to Tom Minka). Considering that the math-functions package
> already has a gamma implementation, it seems it would be natural to
> merge digamma into this package. Alternatively (or additionally), James
> Cook's gamma package also has a variety of gamma implementations and is
> also a candidate for merging digamma into.
>
> I don't mind maintaining digamma, but it might be easier for others if
> there were a single package providing all of these functions. Do others
> have an opinion on this? Are either (or both) of you interested in
> picking up a digamma implementation?


Btw. I did some experiments with approximating the inverse of digamma and 
(exp . digamma). Just in case someone is interested in it:
    http://code.haskell.org/~thielema/htam/src/Numerics/Digamma.hs
    http://code.haskell.org/~thielema/htam/src/Numerics/Digamma/Inverse.hs
    http://code.haskell.org/~thielema/htam/src/Numerics/Digamma/Exponential.hs