def S_e(self, prob):
        """
        The electric source term

        :param Problem prob: FDEM problem
        :rtype: numpy.ndarray
        :return: primary magnetic field
        """
        if all(np.r_[self.mu] == np.r_[prob.curModel.mu]):
            return Zero()
        else:
            formulation = prob._formulation

            if formulation is 'EB':
                mui_s = prob.curModel.mui - 1./self.mu
                MMui_s = prob.mesh.getFaceInnerProduct(mui_s)
                C = prob.mesh.edgeCurl


            elif formulation is 'HJ':
                mu_s = prob.curModel.mu - self.mu
                MMui_s = prob.mesh.getEdgeInnerProduct(mu_s, invMat=True)
                C = prob.mesh.edgeCurl.T

            return -C.T * (MMui_s * self.bPrimary(prob))
dataset/ETHPy150Open simpeg/simpeg/SimPEG/EM/FDEM/SrcFDEM.py/CircularLoop.S_e/original