Re: Re: ! operator
- To: mathgroup at smc.vnet.net
- Subject: [mg55943] Re: [mg55933] Re: [mg55927] ! operator
- From: DrBob <drbob at bigfoot.com>
- Date: Mon, 11 Apr 2005 03:14:52 -0400 (EDT)
- References: <200504110307.XAA06436@smc.vnet.net>
- Reply-to: drbob at bigfoot.com
- Sender: owner-wri-mathgroup at wolfram.com
Hmm... what does "text-based front end" mean, and is there another kind? Is the standard notebook interface a text-based front end? What's an example of a non-text-based front end for Mathematica?
Trace suggests !expr is interpreted the same as Not[expr] for SOME expressions, at least:
But, indeed, if I input:
a DOS window comes up briefly and disappears before I can tell what's up. This is a huge surprise to me.
Type this to see the DOS window more clearly:
Or better yet,
However, if I input
there is no fleeting DOS window, and still no Output cell. Is that because cmd is a DOS command, but PrimeQ isn't? Can Mathematica be certain of this? (True isn't a DOS command, after all.)
Does "escape sequence" mean "DOS command"? No, I guess not, since
doesn't pipe directory contents to a file called "dum.txt". (It doesn't do anything at all, as far as I can tell.) So... what's really going on, I wonder?
On Sun, 10 Apr 2005 23:07:10 -0400 (EDT), David Park <djmp at earthlink.net> wrote:
> Read the rest of the Help for Not, at least on Version 5...
> 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.
> (Certainly a strange 'feature'!)
> David Park
> djmp at earthlink.net
> From: DongGook Park [mailto:dgpark6 at sunchon.ac.kr]
To: mathgroup at smc.vnet.net
> To: mathgroup at smc.vnet.net
> Could you explain a mysterious behaviour of "! operator" as shown below?
> (* Here Mathematica does not give any response! *)
> 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 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
DrBob at bigfoot.com
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