nag_complex_polygamma (s14afc) Example Program Results
       z            k         (d^k/dz^k)psi(z)
(  1.2,   5.0)      0 (   1.6176e+00,    1.4312e+00)
(  0.5,  -0.2)      1 (   3.4044e+00,    2.5394e+00)
( -1.5,   2.5)      1 (  -1.9737e-01,   -2.4271e-01)
(  8.0,   3.3)      3 (   1.1814e-03,   -3.4188e-03)
(  2.9,   7.5)      4 (  -5.0227e-04,   -1.4955e-03)