NTL consists of a number of software modules. Generally speaking, for each module foo, there is a header file <NTL/foo.h>, found in subdirectory include, a documentation file foo.txt, found in subdirectory doc, and a source file foo.cpp, found in subdirectory src. Note that all of the header files for NTL modules include the header file <NTL/tools.h>, and by default, this header file includes the