
				 Drat

   A Yorick package which integrates the transport equation through
			 a quadrilateral mesh


This is a very specialized Yorick package which integrates the
transport equation through a quadrilateral mesh in cylindrical
coordinates.  It is unlikely to be of use to anyone outside my own
narrow specialty (laser fusion research).  I provide it as an example
of a package which "knows" about the interpreter, as opposed to the
Math package, which is a mere installation of LAPACK subroutines into
Yorick.  This "knowledge" is contained in the file ydrat.c, which you
can study if you need to do something similar.

In particular, a new data type -- the "DratMesh" -- is added to the
Yorick interpreter.  This encapsulates the "FullMesh" data structure
which is maintained by the rad-transport package.  This data structure
could not be easily made available to interpreted code, since the
rad-transport code reallocates some of the variable sized data
associated with the "FullMesh"; it wouldn't be nice to attempt to
resize an array the interpreter owned, nor would it be easy to
communicate such a change back to an interpreted data structure.

Also, the interface routines take care of getting their arguments off
of Yorick's stack, which in principle allows them to have a more
general syntax than interpreted functions.  In this case, the only
benefit is that no interpreted "wrapper" routines are required to fix
up the data types and dimensions of input variables before the
compiled routines are called.
