LOAD(ABSIMP); to obtain access to  MACSYMA pattern-matching rules that
extend the built-in simplification rules for the ABS and SIGNUM
functions.  Among other things, use is made of global relations
established with the built-in ASSUME function or by declarations such
as  MODEDECLARE(M,EVEN, N,ODD)  for even or odd integers.  UNITRAMP
and UNITSTEP functions are also defined in terms of ABS and SIGNUM.

Author: David Stoutemyer