[GiNaC-list] psi (digamma) solving

Vladimir V. Kisil kisilv at maths.leeds.ac.uk
Tue Mar 6 10:28:28 CET 2018

On Tue, Mar 6, 2018 at 4:38 AM, Matej Usaj <m.usaj at utoronto.ca> wrote:

> Hi All,
> I'm trying to solve function that contains a call to psi (digamma) but
> my call to fsolve fails every time, ie:
> > f=psi(x/2)==0;
> psi(1/2*x)==0
> > fsolve(f,x,2.7,3.1);
> fsolve(): function does not evaluate numerically
> but I'd expect the result to be x~=2.923...
> Am I missing something here?

Can it be that psi function returns values in terms of the Euler constant?
Then you may need to make float evaluation wrapper for it.

Best wishes,
Vladimir V. Kisil                 http://www.maths.leeds.ac.uk/~kisilv/
  Book:     Geometry of Mobius Transformations     http://goo.gl/EaG2Vu
  Software: Geometry of cycles          http://moebinv.sourceforge.net/
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