#543 limit(atan(sqrt(x))/sqrt(x),x,0) wrong

closed
nobody
5
2007-11-11
2004-03-25
No

limit(atan(sqrt(x))/sqrt(x),x,0) => und

correct answer is 1

limit(...,plus) correctly gets 1
but
limit(...,minus) gives noun form

tlimit gets the correct answer

You might think that limit is being particularly (overly)
careful about the imaginary case, but peculiarly, atan(b^
(3/2))/b^(3/2), which should have the same issues,
gives the correct answer!

Discussion

  • Robert Dodier

    Robert Dodier - 2006-04-09
    • labels: --> Lisp Core - Limit
     
  • Dan Gildea

    Dan Gildea - 2007-11-11

    Logged In: YES
    user_id=1797506
    Originator: NO

    Fixed in limit.lisp rev 1.46.
    Limit now returns nounform if limit from either side fails.

    (%i17) tlimswitch:true;
    (%o17) true
    (%i18) limit(atan(sqrt(x))/sqrt(x),x,0);
    (%o18) 1
    (%i19) limit(atan(sqrt(x))/sqrt(x),x,0,minus);
    (%o19) 1
    (%i20) limit(atan(sqrt(x))/sqrt(x),x,0,plus);
    (%o20) 1
    (%i21) tlimswitch:false;
    (%o21) false
    (%i22) limit(atan(sqrt(x))/sqrt(x),x,0);
    (%o22) 'limit(atan(sqrt(x))/sqrt(x),x,0)
    (%i23) limit(atan(sqrt(x))/sqrt(x),x,0,minus);
    (%o23) 'limit(atan(sqrt(x))/sqrt(x),x,0,minus)
    (%i24) limit(atan(sqrt(x))/sqrt(x),x,0,plus);
    (%o24) 1

     
  • Dan Gildea

    Dan Gildea - 2007-11-11
    • status: open --> closed
     

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