Table 1:

Results of fit parameters for the second-degree 2D polynom from equation 2 and the corresponding χ² misfit values^a

Model	K₀	K₁	K₂	K₃	K₄	K₅	χ²
1	0.2991	−1.2654	0.000341	0.2784	0.001217	−6.489e-07	0.8654
2	0.4665	−1.2684	0^b	0.2784	0.001220	−4.824e-07	0.8662
3	0.9250	−1.2705	−0.000961	0.2784	0.001223	0^b	0.8776
4	−0.0447	−1.0257	0^b	0.2762	0.000985	0^b	1.2019
5	−4.7284	0.0198	0.006848	0.2589	0^b	−2.095e-06	7.1094
6	−2.7584	0.0213	0.002694	0.2585	0^b	0^b	7.238
7	0^b	−1.2563	0.000933	0.2783	0.0012093	−9.321e-07	0.8680
8	0^b	0^b	−0.002664	0.2215	0.0002801	2.1989e-06	6.1559
9	−3.8025	0^b	0.0052012	0.2253	0.0002560	−1.6892e-06	5.7006
10	0^b	−1.0473	0^b	0.2786	0.0009856	0^b	1.2141

Note:—max indicates maximum, min, minimum.
↵a Model 10 is the simplest model (only 3 parameters) with close-to-best accuracy (χ² ≈ χ_min²): maximum positive error = 0.356 V, maximum negative error = −0.326 V.
↵b Values were purposely set to zero to simplify the 2D model and to test their relevance.