## #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
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
2006-10-30

• labels: --> Lisp Core - Limit

• Dan Gildea
2008-02-02

• status: open --> closed

• 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
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
2008-02-03

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user_id=501686
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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.