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MathGroup Archive 2004

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Re: When/why is Denominator[p/q] != q?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg46017] Re: When/why is Denominator[p/q] != q?
  • From: bobhanlon at aol.com (Bob Hanlon)
  • Date: Tue, 3 Feb 2004 03:20:47 -0500 (EST)
  • References: <bvla64$83$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

q is not equal to Denominator[p/q].  In Denominator[p/q] the argument p/q is
evaluated before the Denominator is extracted.  For example,

q=6; Table[{p, p/q, Denominator[p/q]},{p,q-1}]

{{1, 1/6, 6}, {2, 1/3, 3}, {3, 1/2, 2}, {4, 2/3, 3}, {5, 5/6, 6}}


Bob Hanlon

In article <bvla64$83$1 at smc.vnet.net>, relishguy at pluggedin.org (Relishguy)
wrote:

<< I ran this code (from the "Tour of Mathematica" in the Book ):

(* -------------------------------- *)
g6 = Flatten[Table[Point[{p / q, Denominator[p/q]}], {q, 100}, {p, q -
1}]];
(* same code with q instead of Denominator[p/q] *)
g5 = Flatten[Table[Point[{p / q, q  }], {q, 100}, {p, q - 1}]];

Show[Graphics[g5, Frame -> True]]

Show[Graphics[g6, Frame -> True]]
(* -------------------------------- *)


For some reason the graphs are not identical. Can anyone point me to
the reason for this?


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