Hi there, me again
I know that freefem has a function to compute (4.28), but does it have one to compute the average value (4.29)? Couldn’t find anything in the documentation
You have jump and average tool to solve this type of problem, may be,
see Discontinous Galerkin Method,
see https://github.com/FreeFem/FreeFem-sources/blob/master/examples/tutorial/LapDG2.edp for exemple.