Table 2. Accuracy comparison of different approximation methods (two-dimensional case)

Method CL CD
MAE MaxAE R2 MAE MaxAE R2
Kriging 0.4533 1.3197 0.4183 0.0244 0.0871 0.9461
Co-kriging 0.2176 0.8386 0.8609 0.0221 0.0838 0.9032
HK 0.1124 0.6144 0.9530 0.0234 0.0897 0.8918
IHK 0.1560 0.4850 0.9433 0.0216 0.0728 0.9076
3LK 0.1088 0.4297 0.9642 0.0136 0.0502 0.9680