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MathGroup Archive 2005

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Re: ! operator

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55965] Re: [mg55927] ! operator
  • From: János <janos.lobb at yale.edu>
  • Date: Tue, 12 Apr 2005 05:26:18 -0400 (EDT)
  • References: <200504101055.GAA29078@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On my machine:

In[7]:=
Not[MemberQ[{1,2,3},3]]

Out[7]=
False

So it is just he shortcut of ! in place of Not[] which does not work.

In[13]:=
$Version
Out[13]=
"5.1 for Mac OS X (October \
25, 2004)"

János

On Apr 10, 2005, at 6:55 AM, DongGook Park wrote:

>
> Hi,
>
> Could you explain a mysterious behaviour of "! operator" as shown  
> below?
>
>
> In[43]:=
> MemberQ[{1,2,3},3]
>
> Out[43]=
> True
>
> In[47]:=
> !MemberQ[{1,2,3},3]
> (*  Here Mathematica does not give any response!  *)
>
> In[48]:=
> Not@MemberQ[{1,2,3},3]
>
> Out[48]=
> False
>
>
> Considering the description from Mathematica help:
>     "!expr is the logical NOT function. It gives False if expr is  
> True,
> and True if it is False."
> This behaviour seems quite suspicious?
>
>
> DongGook
>
>
> ----------------------------------
> DongGook Park,
> School of Information Technology,
> SunChon University, Korea
> Telephone:  +82 61 750 3597
> Mobile:  +82 18 732 2125
> Home page:  http://www.dgpark6.com/
> Email:  dgpark6 at sunchon.ac.kr
>



----------------------------------------------
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corpse.
(S. Lem: His Master Voice)


  • References:
    • ! operator
      • From: "DongGook Park" <dgpark6@sunchon.ac.kr>
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