After changing the mabs-subst function I get limit(abs(x),x,0) = 0 and
no tests break. I replaced
(COND ((ZEROP1 D) (SETQ D (BEHAVIOR A VAR VAL))
(if (ZEROP1 D) (THROW 'MABS 'RETN))))
with
(if (AND (ZEROP1 D) (ZEROP1 (BEHAVIOR A VAR VAL)))
(SETQ EXP (MAXIMA-SUBSTITUTE A `((MABS) ,ANS) EXP)))
I still don't understand what this BEHAVIOR function does. The MAXIMA
documentation says that the algorithm described in Wangs's Ph.D thesis.
My quesion is, is the thesis available online somethere? I don't think I
can find it in the nearest library here in Russia.
--
Andrei Zorine
Stavros Macrakis wrote:
>>In limit.lisp there's unreacheble code, I think. It's placed in the
>>mabs-subst. It's (COND ... ((AND A D) (COND ((ZEROP1 D)... The second
>>COND is never touched if D is zero. I don't understand this special
>>treating of abs(0). Any comments?
>
>
> 1) I don't understand what you mean by "The second COND is never
> touched". That clause is invoked in processing limit(x*abs(x),x,0), for
> example -- though Limit still doesn't get the answer there!
>
> 2) You might also want to look at the code that is supposed to call
> both-side (see my bug report #782046) for limit's handling of abs -- why
> isn't both-side being invoked for various abs cases?
>
> -s
>
>
>
>