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MathGroup Archive 2006

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RE: Re: MemberQ

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68599] RE: [mg68561] Re: MemberQ
  • From: "Erickson Paul-CPTP18" <Paul.Erickson at Motorola.com>
  • Date: Fri, 11 Aug 2006 04:40:14 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Only curious if for you 
.7//FullForm
doesn't return 0.7000000000000001`

-----Original Message-----
From: leigh pascoe [mailto:leigh at cephb.fr] 
To: mathgroup at smc.vnet.net
Subject: [mg68599] [mg68561] Re: MemberQ

Adriano Pascoletti wrote:
> Bruce Colletti wrote ..
>   
>> Re Mathematica 5.2.0.0.
>>
>> Since 0.7 is in the set {0.0, 0.1, 0.2,..., 0.9, 1.0}, why does 
>> MemberQ[Range[0., 1., .1], .7] return False?
>>  
>> Thankx.
>>
>> Bruce
>>
>>     
>
> Because the 0.7 in Range[0.0, 1.0, 0.1] is
>
> In[11]:=
> Range[0.0,1.0,0.1][[8]]//FullForm
> Out[11]//FullForm=
> 0.7000000000000001`
>
> and
>
> In[9]:=
> FullForm[0.7]
> Out[9]//FullForm=
> 0.7`
>
> They differ on the 16th decimal place as can be seen  evaluating
> 0.7 - Range[0.0, 1.0, 0.1]
>
>
>
> Adriano Pascoletti
>
>
>
>   
So the curious thing is that it returns True for Ssezi and for me!

In[8]:=Range[0.,1.,.1][[8]]//FullForm
MemberQ[Range[0.,1.,.1],.7]

Out[8]//FullForm=0.7000000000000001`

Out[9]=True

LP


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