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_R8Ptype(vector_R8P)::pt(1:2)pt(1)=ex_R8P+ey_R8P+ez_R8Ppt(2)=ex_R8P+ey_R8P-ez_R8Pprint"(L1)",pt(1)/=pt(2)endprogram volatile_doctest