nag_numdiff_1d_real_eval (d04bac) Example Program Results

Find the derivatives of the polygamma (psi) function
using function values generated by nag_real_polygamma (s14aec).

Demonstrate the effect of successively reducing hbase.

 Derivative (1) calculated using nag_real_polygamma (s14aec):    4.0153e+02
 Derivative and error estimates for derivative (1)
         hbase       der[0]     erest[0]
     2.5000e-03   4.0204e+02   1.3940e+02
     2.5000e-04   4.0153e+02   4.9170e-11
     2.5000e-05   4.0153e+02   2.1799e-10
     2.5000e-06   4.0153e+02   1.1826e-09

 Derivative (2) calculated using nag_real_polygamma (s14aec):   -1.6002e+04
 Derivative and error estimates for derivative (2)
         hbase       der[1]     erest[1]
     2.5000e-03  -1.6022e+04   5.5760e+03
     2.5000e-04  -1.6002e+04   1.2831e-07
     2.5000e-05  -1.6002e+04   6.0543e-06
     2.5000e-06  -1.6002e+04   9.5762e-04

 Derivative (3) calculated using nag_real_polygamma (s14aec):    9.6001e+05
 Derivative and error estimates for derivative (3)
         hbase       der[2]     erest[2]
     2.5000e-03   9.1465e+05  -7.3750e+06
     2.5000e-04   9.6001e+05   2.3718e-04
     2.5000e-05   9.6001e+05   4.2253e-02
     2.5000e-06   9.6001e+05   5.9679e+01