Fast Preisach-based vector magnetization model

The Preisach based DOK (Della Torre-Oti-Kadar) model was reformulated to increase its speed of computation so that is could be integrated into a commercial finite element (FE) modeling package. This allowed the FE package to offer a more accurate representation of magnetic material behavior than had been previously available. The next logical step is to offer vector magnetization calculation. Vector models are more complicated, though, due to the cross-coupling effect applied field directions have on magnetization. The simplified vector Preisach model is reformulated here to speed its computations by extending the use of the "cobweb" grid in defining the Preisach function for this multi-dimensional model.