Add to ORKGIn the last decades the magnetic charge method has proven to be an excellent tool to analyze and design permanent magnet based systems. Recent research has shown that inclusion of the relative permeability of magnetic materials is also possible using the extended charge method. Contrary to popular believe, it is also possible to include currents into the equations for the magnetic field using a fictitious magnetization. In this paper the fictitious magnetization is calculated and used to determine the field of a rectangular coil. Compared to the current method to calculate the field, on the same computational hardware and software, a large reduction in calculation time (81 vs 11 seconds) is observed.\u3cbr/\u3e\u3cbr/\u3e\u3cbr/\u3e\u3cbr/\...