Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2005

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

Search the Archive

Re: ! operator

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55940] Re: ! operator
  • From: Peter Pein <petsie at arcor.de>
  • Date: Sun, 10 Apr 2005 23:07:21 -0400 (EDT)
  • References: <d3b18l$sgd$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

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
>
>
From the documentation (topic: Not):
If you are using Mathematica with a text-based front end, then you
cannot use the notation !expr for Not[expr] if it appears at the very
beginning of a line. In this case, !expr is interpreted as a shell escape.

--
Peter Pein
Berlin


  • Prev by Date: Re: cannot evaluate in HelpBrowser (Win XP)
  • Next by Date: Re: ! operator
  • Previous by thread: Re: ! operator
  • Next by thread: Re: ! operator