numerical evaluation of psi0



maxima-bounces at math.utexas.edu wrote on 02/07/2008 09:06:39 AM:

> Barton Willis wrote:
> > I evaluated psi[0](1.78095) using  webMathematica, Maple 10, and 
Maxima
> > 5.14.0 to 50

> You mean that Mma returns something different? 

When I re-did the Mma calculation, all three values agreed. Sorry about 
that.

> > (2) Does anybody have a reference to how our psi function works? It
> > seems to use a modified asymptotic expansion.

> I looked at bffac a while back that is the asymptotic series for log 
> gamma.  A peek at bfpsi shows that it is probably also the asymptotic 
> series for psi.  Probably A&S 6.3.18.

I think there is a clever modification of 6.3.18. If I figure it out, I'll
append a comment. Let's see if we can tweak bfpsi0 to work better in the 
complex plane...

Barton