nag_numdiff_1d_real (d04aac) Example Program Results Four separate runs to calculate the first four odd order derivatives of fun(x) = 0.5*exp(2.0*x-1.0) at x = 0.5. The exact results are 1, 4, 16 and 64 Input parameters common to all four runs xval = 0.500000 nder = -7 (User-supplied callback fun, first invocation.) with step length 0.500000 the results are Order Derivative Error estimate 1 1.3919e+03 -1.0734e+05 3 -3.1386e+03 -1.4378e+05 5 8.7619e+03 -2.4790e+05 7 -2.4753e+04 -4.4838e+05 with step length 0.050000 the results are Order Derivative Error estimate 1 1.0000e+00 1.5294e-11 3 4.0000e+00 2.1125e-09 5 1.6000e+01 3.8149e-07 7 6.4000e+01 7.3845e-05 with step length 0.005000 the results are Order Derivative Error estimate 1 1.0000e+00 1.2768e-14 3 4.0000e+00 4.1903e-10 5 1.6000e+01 1.4629e-05 7 6.4039e+01 2.9729e-01 with step length 0.000500 the results are Order Derivative Error estimate 1 1.0000e+00 1.4266e-13 3 4.0000e+00 3.0869e-07 5 1.5988e+01 6.3314e-01 7 3.8249e+04 -1.9644e+06