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Re: Bug with Limit?

• To: mathgroup at smc.vnet.net
• Subject: [mg73921] Re: Bug with Limit?
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Sat, 3 Mar 2007 01:02:35 -0500 (EST)
• Organization: The Open University, Milton Keynes, UK
• References: <es91g4$34b$1@smc.vnet.net>

Sergio Miguel Terrazas Porras wrote:
> Hi guys,
>  
> I was teaching a class and was discussing discontinuous functions.
> We came across f(x) = Abs(x)/x, and g(x) = 1/(x-3).
> The first does not have a limit as x -> 0 and the second does not have a
> limit as x -> 3.
> The unilateral limits of both are different.
> When I specified the direction, Mathematica 5.1 gave the correct answer.
> However, when no direction was specified, Mathematica 5.1 gave (seemingly)
> by default the value of de right handside limit.
>  
> This is plain wrong, and could lead to problems, specially for a student.
> Any comments?
>  
> Thank you.
> Sergio Terrazas
> 

The following thread "Calculus: limits", among many others about the 
same subject (just google comp.soft-sys.math.mathematica), already 
contents numerous comments:

http://groups.google.com/group/comp.soft-sys.math.mathematica/browse_thread/thread/35518b2c019c9fed/25c0f5767d75ef2f?lnk=gst&q=limit+helen&rnum=1#25c0f5767d75ef2f

Regards,
Jean-Marc