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Re: Limit bug in Calculus\Limit ???

• To: mathgroup at smc.vnet.net
• Subject: [mg8523] Re: [mg8488] Limit bug in Calculus\Limit ???
• From: David Withoff <withoff>
• Date: Thu, 4 Sep 1997 02:20:22 -0400
• Sender: owner-wri-mathgroup at wolfram.com

> I am using Mma 3.0 on a NextStep 3.3 PentiumPro Intel machine;  I
> have also successfully reproduced the problem on a Sparc running Mma
> 3.0.
>
> The following command
>
>       Limit[E^(2/y),y->0]
>
> returns the correct answer "infinity" when the Calculus`Limit`
> package IS NOT loaded.  When the Limit package IS_loaded (which I had
> thought meant even more functionality), I incorrectly obtain "0" as
> the answer.
>
> Why is the Limit.m generating an incorrect answer?  Is this a known
> bug?  And if so, is there a list of known bugs that a user can
> access?

Actually, since this limit depends on direction, both answers
are arguably correct.

In[1]:= Limit[E^(2/y), y -> 0, Direction -> 1]

Out[1]= 0

In[2]:= Limit[E^(2/y), y -> 0, Direction -> -1]

Out[2]= Infinity

The Calculus`Limit` package installs different functionality, rather
than adding more functionality.  That is, the Calculus`Limit` package
removes the built-in Limit function, and replaces it with a different
function and with a different algorithm.   Additional information about
this can be found by reading the Calculus`Limit` package, or in the
technical support section of the Wolfram Research web site.

Dave Withoff
Wolfram Research