Validity of the measured equation of invariance

The measured equation of invariance (MEI) is derived without any postulates. It is shown that the coefficients of the MEI are invariant to the field of excitation. However, the accuracy of the MEI solution is closely related to the number of nodes in the MEI. Coupling more nodes improves progressively the accuracy of the MEI solution. With increasing nodes, the matrix problem for the determination of the MEI coefficients becomes seriously ill conditioned and generally must be solved using multiple precision arithmetic. The consequences of the ill-conditioning phenomenon are discussed.