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Date:      Wed, 15 Jan 2003 11:26:31 +0100
From:      Erik Trulsson <ertr1013@student.uu.se>
To:        "P. U. Kruppa" <520023893678-0001@t-online.de>
Cc:        Kevin Stevens <Kevin_Stevens@pursued-with.net>, Alex.Wilkinson@dsto.defence.gov.au, freebsd-questions@FreeBSD.ORG
Subject:   Re: entropy
Message-ID:  <20030115102631.GA12993@falcon.midgard.homeip.net>
In-Reply-To: <20030115084451.U2608-100000@small.pukruppa.de>
References:  <AD7DCC42-285B-11D7-9D3C-003065715DA8@pursued-with.net> <20030115084451.U2608-100000@small.pukruppa.de>

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On Wed, Jan 15, 2003 at 08:51:35AM +0000, P. U. Kruppa wrote:
> On Tue, 14 Jan 2003, Kevin Stevens wrote:
> 
> >
> > On Tuesday, Jan 14, 2003, at 22:46 US/Pacific, Wilkinson,Alex wrote:
> >
> > > Can someone recommend to me where I can read up on
> > > entropy.
> > >
> > > ie what it is ? Why we have it ? etc etc
> > >
> > >  - aW
> >
> > Entropy is a tendency towards disorder in the universe, exemplified by
> > things LIKE SOME FREAKIN' CLUELESS GIT POSTING A TOTALLY OFF-TOPIC
> > SCIENCE MESSAGE TO A COMPUTER OS LIST!!!

No need to be rude.

> Entropy also evaluates information and is measured in so called
> bits .

Indeed.  See random(4) for information on what FreeBSD uses entropy
for. (Short version: Generating random numbers.) (So, no, this is not
totally off-topic.)

> The original work about this was written (I think in the
> sixties) by two authors:  Shannon/Weaver
> Sorry, I don't know the title: it was something with information
> theory.

You are thing of a reprint of the original article which was
"A mathematical theory of communication" by Claude Shannon, 1948.
It is fairly easy to find a copy of this paper on the 'Net.
The paper is actually quite readable, and strongly recommended for
anybody interested in information theory or cryptology.

> 
> Regards,
> 
> Uli.
> 
> 
> >
> > Did you actually have to MOVE your browser from in front of the mail
> > program to AVOID searching for this on the web?!?

You DO know that it is quite possible to be able to send and receive
e-mail while not being directly connected to the Internet and therefore
not being able to check the WWW?
(Granted, this is quite unusual today, but still a possibility.)


> >
> > KeS
> >
> >
> > OB-FreeBSD:
> > /usr/ports/math/entropy
> > "Entropy is a program that will calculate the entropy of a given set
> > of data. This program is mainly used to benchmark the efficiency
> > of existing or developing compression algorithms."
> >


-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013@student.uu.se

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