Hi,
judging from what the maual says about derivabbrev, I think it should
affect only the way expressions are displayed, and not affect calculations.
Using the default value of derivabbrev, the following (nonsense example)
is ok:
(%i1) derivabbrev;
(%o1) false
(%i2) defrule(
dr,
'diff(aa,bb,cc),
foo
);
(%o2) dr:'diff(aa,bb,cc)->foo
However, using derivabbrev: true, I get an error
(%i3) derivabbrev: true;
(%o3) true
(%i4) defrule(
dr,
'diff(aa,bb,cc),
foo
);
Maxima encountered a Lisp error:
Error in > [or a callee]: $CC is not of type (OR RATIONAL LISP:FLOAT).
Automatically continuing.
To reenable the Lisp debugger set *debugger-hook* to nil.