Expression of Concern: Improving the generality of the fictitious magnetic charge approach to computing inductances in the presence of permeable materials

In this paper we present an improvement to the fictitious magnetic charge approach to computing inductances in the presence of permeable materials. The improvement replaces integration over a "non-piercing" surface with a line integral and an efficient quadrature scheme. Eliminating the need to generate non-piercing surfaces substantially simplifies handling problems with general geometries of permeable materials. Computational results are presented to demonstrate the accuracy and versatility of the new method.