No Subject
- To: mathgroup@smc.vnet.net
- From: Andrzej Kozlowski <andrzej@tuins.ac.jp>
- Date: Fri, 30 Jan 1998 04:24:12 -0500
In article <6ahorb$pkh@smc.vnet.net>, seanross@worldnet.att.net wrote:
> alok. menghrajani wrote:
> >
> > Hi,
> >
> > I'm 16 and I can't understand how I (why me?) found this bug in
> > mathematica. It's such a silly thing:
> >
> > Solve [x/x+x=1, x] returns x=0 but if x=0 then x/x has no sence!
> >
> > Bye, ALok
> >
> > (Pls reply to my email: robot@writeme.com)
>
>
> Its not a bug. You are missing a pre-calculus course in limits. Perhaps
> your high school offers one.
It may sound very pedantic but I must say I feel this reply is a little
unfair to Alok. The equation x/x+x== 1 is an algebraic equation and
the solution {x->0} is certainly incorrect. I would fail any of my
students who claimed it was, so I do not think his pointing this out is
a sign of ignorance of mathematics. (To make it quite clear you can
replace Alok's equation by
Solve[{x/x+x==1,Modulus==5},x,Mode->Modular]. You still get the same
answer though it now makes no sense to talk about limits). The reason
why this is not a bug seems to me, basically, to be the fact that we
expect of computers other things than of algebra students. In
particular, in computer algebra strict mathematical correctness often
takes second place to considerations such as speed, efficiency etc. I
think one has to remember that when claiming that behaviour which does
not correspond to standard mathematical practice constitutes a bug (I
have found several such examples in the past archives of mathgroup).
A. Kozlowski