A new linear transfer function defined by any Laplace transform in the s-variable.
SIMetrix has offered a Laplace Transfer Function feature for many years but the earlier implementation only supported Laplace Transforms that could be expressed as a quotient of polynomials. This could not be used, for example, to implement skin-effect models which require a square root function.
The new Laplace feature accepts a much wider range of Laplace Transforms including square roots, exponentials and look-up tables.
As the Laplace Transform is a frequency domain description of a transfer function, implementation in the time domain, presents some difficulties. The traditional method using simple convolution is often too slow to be practical in many applications as the whole history to time zero has to be processed for each time step.
To overcome this, SIMetrix uses a multi-level FFT method to perform the convolution; this method is orders of magnitude faster in many applications.
