Re: [Maxima-discuss] rule issue

[Robert D. <rob...@gm...>]

On 2014-06-29, Dimiter Prodanov <dim...@gm...> wrote:

> (matchdeclare (u, atom, fn, symbolp),
> defrule (ddint21, 'integrate(delta(u)*fn(u), u, minf, inf), fn(0))
> );
>
>>> ddint21('integrate(delta(u)*fn(u), u, minf, inf));
> output false
> should be
> fn(0)

That's a bug in the function which is generated for that rule.
I've appended the generated code below -- you can see that TR-GENSYM7
is referenced but without being assigned a value before. I suspect
that the (KAAR TR-GENSYM7) should be (KAAR TR-GENSYM3). (An alternative
suspicion is that the immediately preceding (SETQ TR-GENSYM3 ...) should
be (SETQ TR-GENSYM7 ...).) 

I'll look at fixing the bug although it might be tricky to figure it
out. A work-around is to phrase the rule in a different way which
doesn't trigger the bug; here's an example. There are probably other
formulations that also work.

  (%i1) display2d : false $
  (%i2) matchdeclare (aa, all, xx, symbolp) $
  (%i3) simp : false $
  (%i4) defrule (r1, 'integrate(delta(xx)*aa, xx, minf, inf), subst (xx = 0, aa)) $
  (%i5) simp : true $
  (%i6) r1 ('integrate (delta(u)*f(u)*g(t - u), u, minf, inf));
  (%o6) f(0)*g(t)

best

Robert Dodier

PS. 
I'm working with Clisp.

:lisp #'$ddint21
#<FUNCTION LAMBDA (TR-GENSYM1) (DECLARE (SPECIAL TR-GENSYM1))
  (CATCH 'MATCH
   (PROG
    ($FN $U TR-GENSYM2 TR-GENSYM3 TR-GENSYM4 TR-GENSYM5 TR-GENSYM6 TR-GENSYM7 TR-GENSYM8 TR-GENSYM9 TR-GENSYM10 TR-GENSYM11
     TR-GENSYM12 TR-GENSYM13)
    (DECLARE
     (SPECIAL $FN $U TR-GENSYM2 TR-GENSYM3 TR-GENSYM4 TR-GENSYM5 TR-GENSYM6 TR-GENSYM7 TR-GENSYM8 TR-GENSYM9 TR-GENSYM10
      TR-GENSYM11 TR-GENSYM12 TR-GENSYM13))
    (COND ((NOT (EQUAL (KAAR TR-GENSYM1) '%INTEGRATE)) (MATCHERR))) (SETQ TR-GENSYM2 (KDR TR-GENSYM1))
    (SETQ TR-GENSYM3 (KAR TR-GENSYM2)) (SETQ TR-GENSYM4 (FINDFUN TR-GENSYM3 (MEVAL '$DELTA) 'MTIMES))
    (SETQ TR-GENSYM5 (KDR TR-GENSYM4)) (SETQ TR-GENSYM6 (KAR TR-GENSYM5))
    (COND ((DEFINITELY-SO '(($ATOM) TR-GENSYM6)) (MSETQ $U TR-GENSYM6)) ((MATCHERR))) (COND ((NTHKDR TR-GENSYM5 1) (MATCHERR)))
    (SETQ TR-GENSYM3 (MEVAL '((MQUOTIENT) TR-GENSYM3 (($DELTA SIMP) $U)))) (MSETQ $FN (KAAR TR-GENSYM7))
    (SETQ TR-GENSYM8 (FINDFUN TR-GENSYM3 $FN 'MTIMES)) (SETQ TR-GENSYM9 (KDR TR-GENSYM8)) (SETQ TR-GENSYM10 (KAR TR-GENSYM9))
    (COND ((NOT (ALIKE1 TR-GENSYM10 (MEVAL '$U))) (MATCHERR))) (COND ((NTHKDR TR-GENSYM9 1) (MATCHERR)))
    (SETQ TR-GENSYM3 (MEVAL '((MQUOTIENT) TR-GENSYM3 (($FN SIMP) $U)))) (COND ((NOT (EQUAL TR-GENSYM3 1)) (MATCHERR)))
    (SETQ TR-GENSYM11 (KAR (KDR TR-GENSYM2))) (COND ((NOT (ALIKE1 TR-GENSYM11 (MEVAL '$U))) (MATCHERR)))
    (SETQ TR-GENSYM12 (KAR (KDR (KDR TR-GENSYM2)))) (COND ((NOT (ALIKE1 TR-GENSYM12 (MEVAL '$MINF))) (MATCHERR)))
    (SETQ TR-GENSYM13 (KAR (KDR (KDR (KDR TR-GENSYM2))))) (COND ((NOT (ALIKE1 TR-GENSYM13 (MEVAL '$INF))) (MATCHERR)))
    (COND ((NTHKDR TR-GENSYM2 4) (MATCHERR))) (RETURN (VALUES (MEVAL '(($FN SIMP) 0)) T))))>