Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

May we trust IntegerQ ?

• To: mathgroup at smc.vnet.net
• Subject: [mg107488] May we trust IntegerQ ?
• From: Artur <grafix at csl.pl>
• Date: Sun, 14 Feb 2010 08:16:41 -0500 (EST)
• Reply-to: grafix at csl.pl

Procedure: find such x that ChebyshevT[x/2, x] isn't integer
aa = {}; Do[ If[IntegerQ[ChebyshevT[x/2, x]], , AppendTo[aa, x]], {x, 0, 
20}]; aa
and answer Mathematica is set:
{3, 5, 7, 9, 11, 13, 15, 17, 19}
where occered e.g. number 7
N[ChebyshevT[7/2, 7],100]
5042.00000000000000000000000000000000000000000000000000000000000000000\
0000000000000000000000000000000
evidently is integer 5042
Some comments ?

Best wishes
Artur

• Follow-Ups:
  • Re: May we trust IntegerQ ?
    • From: danl@wolfram.com
  • Re: May we trust IntegerQ ?
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
  • Re: May we trust IntegerQ ?
    • From: Patrick Scheibe <pscheibe@trm.uni-leipzig.de>