An optimal transformation for a given field and PML geometry is one which transforms the field to have a linear variation through the PML. This repo is a Julia implementation of this idea, which was described in my PhD thesis submitted to the University of Manchester.
To install this package, call
import Pkg
Pkg.add("https://github.com/jondea/OptimalPMLTransformations.jl")or alternatively type ] add https://github.com/jondea/OptimalPMLTransformations.jl
in the REPL.