Use of stream functions for the computation of currents in thin circuits determination of the impedances

We compute the currents appearing in a circuit of very small thickness when a voltage is applied to its ends or when it is put into an inductive electric field. The discretization of the problem uses stream functions and then there is only one scalar variable related to each node of the mean surface of the circuit; the computation is very fast. Moreover, it is immediately usable to deduce the global current which appears and then it is very easy to obtain the circuit impedance.