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MathGroup Archive 1997

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Q: Union and precision.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg8529] Q: Union and precision.
  • From: Gadi Oron <oron at manet.pmmh.espci.fr>
  • Date: Thu, 4 Sep 1997 02:20:33 -0400
  • Organization: Acces regional Ile-de-France (Univ. Paris VI/VII) - France
  • Sender: owner-wri-mathgroup at wolfram.com

Hello again,

How can I force Union to consider numbers equal in the current 
precision as equal? Explanation:

In:= 	a=SetPrecision[1.234567,2]
Out:= 	1.2

In:= 	b=SetPrecision[1.234561,2]  (* Notice difference *)
Out:= 	1.2

In:= 	a==b
Out:=	True

In:=	Union[{a,b}]
Out:=	{1.2,1.2} (* !!! *)

How does Union evaluates equalities? How can I force it to do it the right
way??
  
Thanx.
/\/\/\/\/\/\/\/\/\/\/\/>> Gadi ORON <<\/\/\/\/\/\/\/\/\/\/\/\/\
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