ftnchek (short for Fortran checker) is designed to detect certain errors
in a Fortran 77 program that a compiler usually does not.  ftnchek is not
primarily intended to detect syntax errors.  Its purpose is to assist the
user in finding semantic errors.  Semantic errors are legal in the Fortran
77 language but are wasteful or may cause incorrect operation.  For example,
variables which are never used may indicate some omission in the program;
uninitialized variables contain garbage which may cause incorrect results
to be calculated; and variables which are not declared may not have the
intended type.  ftnchek is intended to assist users in the debugging of
their Fortran 77 program.  It is not intended to catch all syntax errors.
This is the function of the compiler.  Prior to using ftnchek, the user
should verify that the program compiles correctly.

WWW:  http://www.dsm.fordham.edu/~ftnchek/
