Nodes of different colours represent the following:
Solid arrows point from a file to a file which it depends on. A file
is dependent upon another if the latter must be compiled before the former
can be.
program volatile_doctestuse vecfor_RPPtype(vector)::pt(0:2)real(R8P)::dpt(0)=5.3*ezpt(1)=expt(2)=eyd=distance_to_line(pt(0),pt1=pt(1),pt2=pt(2))print"(F3.1)",dendprogram volatile_doctest