public elemental function ply_lambda(val) result(funcVal)
\todo: as we use a relation of gamma, it might be better to use the
gammln function provided by the numerical recipes, and just
use the difference in an exponential function.
Nodes of different colours represent the following:
Solid arrows point from a procedure to one which it calls. Dashed
arrows point from an interface to procedures which implement that interface.
This could include the module procedures in a generic interface or the
implementation in a submodule of an interface in a parent module.