I just submitted two fixes for a trivial and an easy taylor bug I found.
Unfortunately, the ONE taylor bug I tried to fix I couldn't, but I have
a clue now:
taylor(sum(M^K*sum(L^K,L,1,D),K,1,INF),M,0,2),simpsum;
gives a nearly correct answer, only the L's should be replaced by D's...
It appears that the error occurs when fpolysum in combin.lisp is called.
fpolysum in turn is
(defun fpolysum (e) ;returns *ans*
(let ((a (fpoly1 (setq e ($expand ($ratdisrep ($rat e *var*))))))
and within the ratdisrep rat stuff the following happens:
usually a rat expression is
((MRAT SIMP <varlist> <genvar> <tlist> trunc) <poly-form>)
where varlist and genvar have the same length.
Here they don't, quite on the contrary, genvar contains quite some rubbish
I do not REALLY understand where it could come from.
My question is:
should varlist and genvar really always have the same length or is this
not required?
where should I look to now?
Martin