A method is proposed in which the locations and electric current vectors of multiple biomagnetic current dipoles can be estimated without a priori information regarding the exact number of dipoles. In this method, an additional constraint is used in the cost function in conjunction with a constraint regarding degree of matching between estimated dipole parameters and a measured magnetic field. Two constraints, a constraint on the sum of current magnitude and that on the sum of each dipole's contribution on measured data, are proposed as the additional constraint in this paper. Computer simulation clearly shows that çither constraint can be effectively used to suppress the ambiguity caused by the lack of information regarding the exact number of dipoles. Since the cost function becomes highly nonlinear, the simulated annealing algorithm1,2 is essential to search for the minimum of the cost function.
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