nag_numdiff_fwd (d04aac) Example Program Results Four separate runs to calculate the first four odd order derivatives of f(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 f, first invocation.) with step length 0.5000 the results are Order Derivative Questionable? 1 --------- Yes 3 --------- Yes 5 --------- Yes 7 --------- Yes with step length 0.0500 the results are Order Derivative Questionable? 1 1.00e+00 No 3 4.00e+00 No 5 1.60e+01 No 7 6.40e+01 No with step length 0.0050 the results are Order Derivative Questionable? 1 1.00e+00 No 3 4.00e+00 No 5 1.60e+01 No 7 6.40e+01 No with step length 0.0005 the results are Order Derivative Questionable? 1 1.00e+00 No 3 4.00e+00 No 5 1.60e+01 No 7 --------- Yes