#1016 limit(floor(x),x,1) wrong

closed
nobody
5
2008-02-02
2006-10-30
Anonymous
No

With Maxima version: 5.10.0, I get the following :

(%i1) limit(floor(x),x,1);
(%o1) 1
should be und

(%i2) limit(floor(x),x,1,minus);
(%o2) 1
should be 0

Eric Reyssat
email : reyssat@math.unicaen.fr

Discussion

  • Robert Dodier
    Robert Dodier
    2006-10-30

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    limit is mistakenly assuming that floor is continuous. I
    don't know how to make limit recognize that floor is
    discontinuous.

    Assigning this report to the "Lisp Core - Limit" category.

     
  • Robert Dodier
    Robert Dodier
    2006-10-30

    • labels: --> Lisp Core - Limit
     
  • Dan Gildea
    Dan Gildea
    2008-02-02

    • status: open --> closed
     
  • Dan Gildea
    Dan Gildea
    2008-02-02

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    Returns noun form as of limit.lisp 1.50:

    (%i4) limit(floor(x),x,1);
    (%o4) 'limit(floor(x)+1,x,0)
    (%i5) limit(floor(x),x,1,minus);
    (%o5) 'limit(floor(x)+1,x,0,minus)

     
  • Robert Dodier
    Robert Dodier
    2008-02-02

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    I dunno. A noun form is useful if some additional information would make it possible to resolve it to some more definite result. But for 'limit(floor(x)+1,x,0) there isn't any such additional info, from what I can tell. So I think limit(floor(x),x,1) should yield und.

    Also it seems limit(floor(x),x,1,minus) should yield 0, not a noun expression.

    I guess the noun expressions are not incorrect, but they're not correct either.

    By the way, Dan, thanks a lot for all the bug fixes you have made. I appreciate it a lot.

     
  • Robert Dodier
    Robert Dodier
    2008-02-03

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    I dunno. A noun form is useful if some additional information would make it possible to resolve it to some more definite result. But for 'limit(floor(x)+1,x,0) there isn't any such additional info, from what I can tell. So I think limit(floor(x),x,1) should yield und.

    Also it seems limit(floor(x),x,1,minus) should yield 0, not a noun expression.

    I guess the noun expressions are not incorrect, but they're not correct either.

    By the way, Dan, thanks a lot for all the bug fixes you have made. I appreciate it a lot.