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Re: Bug ???

• To: mathgroup at smc.vnet.net
• Subject: [mg81838] Re: Bug ???
• From: Peter Pein <petsie at dordos.net>
• Date: Thu, 4 Oct 2007 04:33:02 -0400 (EDT)
• References: <200710020928.FAA28247@smc.vnet.net> <200710030635.CAA29450@smc.vnet.net> <fdvra7$qrb$1@smc.vnet.net>

Artur schrieb:
> Why doesn't work:
> a={};Do[k=n^2-(Floor[n^2(2/3)])^2;If[k=0,
> AppendTo[a,{k,n^2}]],{n,1,1000}];a
> but working
> a={};Do[k=n^2-(Floor[n^2(2/3)])^2;If[k<1,
> AppendTo[a,{k,n^2}]],{n,1,1000}];a
> 
> Artur Jasinski, Poland
> 
> 

Hi Artur,

1. If [k=0,...] assigns 0 to k and becomes If[0,...] and 0 != True.
2. k<1 is a completely other test than k==0.

But wouldn't it be much easier to use
{{0, n^2}} /. ToRules @ Reduce[Floor[2n^2/3] == n > 0, n, Integers]
to get the same result?
(and is it necessary to use a CAS for this anyway)?

Peter

• References:
  • help with polynomial solutions
    • From: "Jules P. Aronson" <aronson@nlm.nih.gov>
  • Re: help with polynomial solutions
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>