Meaning of form compiler options, viz: epsilon

Question

What is the meaning of the 'epsilon' entry in the form_compiler parameters?

parameters["form_compiler"]["epsilon"] = ??

Moreover, is there is a listing of the parameters and their meanings? Some are self explanatory but some (epsilon, form_postfix, split, restrict_keyword) are unclear (to my "FEniCS User" level of experience anyway)

Thanks,

Answer 1

Some options, e.g. split, are explained in

man ffc

epsilon is used in code generation to define how small values should be considered zero for tables of precomputed values. The other listed options are nothing to worry about.