.\" @(#)introduction	2.8 12/3/91
.H1 "Introduction"
.pp
\*(PT provides rich libraries of stars for each domain.
Since the stars in the libraries were designed to be as 
generic as possible, many complicated functions can be
realized by a galaxy of those stars.  Nonetheless, no star
library can possibly be complete; you may need to design your own stars.
For this purpose, the Ptolemy preprocessor language was devised.
The main part of this chapter is devoted to the usage of the
preprocessor language.  
.pp
The newly designed stars can be dynamically linked into \*(PT
when they are required, which avoids the hassle of frequent
recompilation of the system.  If the new stars are generic and
useful, however, it might be better to add them to the list of
compiled-in stars and rebuild the system.  This chapter explains
what procedure should be followed to add or modify stars into the
libraries.
