Raytrace Simulation

The critical API for raytrace simulation are the psiXvalue(x,y) and psiYvalue(x,y), which gives the two elements of $\nabla\psi(x,y)$. These are defined by the Lens class.

Subclasses of PsiFunctionLens class implement psiXvalue(x,y) and psiYvalue(x,y) by calculating algebraic expressions for the partial derivatives of $\psi$. To enable raytrace simulation with new lens models, all that is needed is a subclass implementing these two functions.

Sampled lenses implement psiXvalue(x,y) and psiYvalue(x,y) using differentiation filters. To make a new subclass of PsiFunctionLens work with sampled simulation (using the SampledPsiFunctionLens), all that is need is the psiValue(x,y) function which evaluates $\psi$.