The Si9000 incorporates field solving for single-ended and differential impedance structures. The discrete numerical analysis in the Si9000 uses Boundary Element Method to evaluate the residual field. A piecewise linear approximation is used with a weighted sub-division of the perimeter of the trace cross-section to predict the surface charge distribution on the trace. Knowing the boundary voltage conditions and the charge distribution allows evaluation of the Green's Function using Method of Moments integration to predict the capacitance of the structure. This in turn allows the impedance of the structure to be calculated.