REDUCE_CONSTS(exp) replaces constant subexpressions of EXP with
constructed constant ATOMs, saving the definition of all these
constructed constants in the list of equations CONST_EQNS, and
returning the modified EXP.  Those parts of EXP are constant which
return TRUE when operated on by the function CONSTANTP.  Hence,
before invoking REDUCE_CONSTS, one should do

DECLARE([<list of objects to be given the constant property>],CONSTANT)$

to set up a database of the constant quantities occurring in your
expressions.

   If you are planning to generate FORTRAN output after these symbolic
calculations, one of the first code sections should be the calculation
of all constants.  To generate this code segment, do

MAP('FORTRAN,CONST_EQNS)$

   Variables besides CONST_EQNS which affect REDUCE_CONSTS are:

      CONST_PREFIX['xx] is the string of characters used to prefix all
symbols generated by REDUCE_CONSTS to represent constant subexpressions.

      CONST_COUNTER[1] is the integer index used to generate unique
symbols to represent each constant subexpression found by REDUCE_CONSTS.

   To use REDUCE_CONSTS, do LOAD(RDUCON)$ .  A demonstration is given
in SHARE1;RDUCON DEMO .  Bugs to GCOOK@MIT-MC .