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Re: different output!!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg97034] Re: different output!!
  • From: olfa <olfa.mraihi at yahoo.fr>
  • Date: Tue, 3 Mar 2009 05:56:00 -0500 (EST)
  • References: <godm3n$46c$1@smc.vnet.net> <gogc32$oib$1@smc.vnet.net>

On 2 mar, 11:23, "Sjoerd C. de Vries" <sjoerd.c.devr... at gmail.com>
wrote:
> It seems correct to me. Please note that Mod[x,5] is not necessarily
> integer and therefore not countable if x is a real whereas it is
> countable when x is an integer. Reduce does a fine job here.
>
> Cheers -- Sjoerd
>
> On Mar 1, 11:56 am, olfa <olfa.mra... at yahoo.fr> wrote:
>
>
>
> > Hi Mathematica community,
> > Why output2 (with integers as domain) is different from output1 (with
> > reals as domain) ?!! I think it should be the same thing.
>
> > input1:Reduce[{Mod[x, 5] == Mod[xP, 5], 0 <= xP < 5}, {xP}, Reals=
,
> >  Backsubstitution -> True]
>
> > output1: 0 <= Mod[x, 5] < 5 && xP == Mod[x, 5]
>
> > input2:Reduce[{Mod[x, 5] == Mod[xP, 5], 0 <= xP < 5}, {xP}, Integ=
er=
> s,
> >  Backsubstitution -> True]
>
> > output2: (Mod[x, 5] == 0 && xP == 0) || (Mod[x, 5] == 1 &&
> >    xP == 1) || (Mod[x, 5] == 2 && xP == 2) || (Mod[x, 5=
] =
> == 3 &&
> >    xP == 3) || (Mod[x, 5] == 4 && xP ==
> > 4)- Masquer le texte des messages pr=E9c=E9dents -
>
> - Afficher le texte des messages pr=E9c=E9dents -

What I mean is that I want to represent output2 by: Mod[x,5] belongs
to Integers and 0<=Mod[x,5]<5 and xP==Mod[x,5], is it possible?should
I add something in reduce to have this output.


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