The strange behaviour of glngamma

[Olivier Ramare <ramare@agat.univ-lille1.fr>]

Dear all,

  glngamma has its argument between -Pi and Pi ....
So it is discontinuous. I would have expected it to
be continuous and with argument 0 on the real line.
That what I stupidly understood by "principal branch".
Any way to hack the existing code for that purpose ?
  Best,
  Amities,
            Olivier