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Re: Applying Mathematica to practical problems

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• Subject: [mg131020] Re: Applying Mathematica to practical problems
• From: Andrzej Kozlowski <akozlowski at gmail.com>
• Date: Tue, 4 Jun 2013 01:59:23 -0400 (EDT)
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On 3 Jun 2013, at 17:14, Richard Fateman <fateman at EECS.Berkeley.EDU> wrote:

> On 6/3/2013 8:01 AM, Richard Fateman wrote:
> I said..
> Solve[x+1==x,x] returns {}
> yet
> 1`0 +1`0 == 1`0 returns True.
>
> oops.  make that last line 1`0+1 == 1`0 .
>
> Changing the semantics of ==  to the semantics of === may help
> in some circumstances, but it seems to me we went through this
> before.
> RJF

I forgot to deal with this little thing. Solve solves over the (exact) complex numbers. 1`0  is not an exact real number hence it is not an exact complex number. Non-exact reals and complexes are not included so your "proof" is just a bluff.

Andrzej Kozlowski

PS. I realize that Mathematica gives:

Element[1`0, Reals]

True

I have never liked this and I think it ought to be changed (unless something important depends on this).

• References:
  • Re: Applying Mathematica to practical problems
    • From: Richard Fateman <fateman@cs.berkeley.edu>