Table 1.

Performance Values for 10 Shim Axes Designed Using Minimum Inductance and Minimum Power Algorithms

		Inductive Merit			Resistive Merit
Axis	Analysis	Minimum Power Method	Minimum Inductance Method	Percent Difference	Minimum Power Method	Minimum Inductance Method	Percent Difference
Z	Discrete	0.0957	0.101	5.40	0.00490	0.00460	6.32
	Continuous	0.0937	0.100	6.97	0.00620	0.00570	8.4
Z2	Discrete	0.797	0.839	5.13	0.0373	0.0340	9.26
	Continuous	0.816	0.869	6.29	0.0462	0.0413	11.2
Z3	Discrete	10.5	11.2	6.45	0.418	0.395	5.65
	Continuous	10.3	11.1	7.48	0.545	0.505	7.61
Z4	Discrete	91.5	93.4	5.50	3.3282	3.0998	7.10
	Continuous	88.2	90.4	6.25	4.41	4.01	9.50
X and Y	Discrete	0.0870	0.0921	5.69	0.00400	0.00350	13.3
	Continuous	0.0879	0.0933	5.96	0.00520	0.00450	14.4
XY and X2–Y2	Discrete	1.53	1.63	6.33	0.0589	0.0535	9.6
	Continuous	1.53	1.62	5.71	0.0799	0.0718	10.7
YZ and XZ	Discrete	2.14	2.34	8.93	0.0625	0.0581	7.29
	Continuous	2.17	2.33	7.11	0.0844	0.0752	11.53

In every design case, the improvement in ML provided by the minimum inductance method is <10% of the value obtained using the minimum power method and the improvements in MR provided by the minimum power method are <15% of the values obtained using the minimum inductance method. The merit of inductance calculated with the discrete method agrees with the merit of inductance calculated with the continuous method within 3.5% in all cases. The difference between the merits of power calculated with the discrete and the continuous methods ranges between 10% and 30%.