[25301] in Perl-Users-Digest
Perl-Users Digest, Issue: 7546 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Dec 21 06:05:46 2004
Date: Tue, 21 Dec 2004 03:05:07 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Tue, 21 Dec 2004 Volume: 10 Number: 7546
Today's topics:
Re: change mac address formatting in a regex <someone@example.com>
Re: inserting a line into the body of an eMail before f <noreply@gunnar.cc>
Re: Is zero even or odd? <zerospam@yahoo.com>
Re: Is zero even or odd? (Don Klipstein)
Re: Is zero even or odd? <salesEXTRACT@anasoft.co.uk>
Re: Is zero even or odd? <salesEXTRACT@anasoft.co.uk>
Re: Is zero even or odd? <bond@bondo.net>
Re: Is zero even or odd? <bond@bondo.net>
Re: Is zero even or odd? <ben_nospam_bradley@mindspring.com>
Re: Is zero even or odd? <josef.moellers@fujitsu-siemens.com>
Re: Is zero even or odd? mmeron@cars3.uchicago.edu
Re: Is zero even or odd? <jmw@jmwa.demon.contraspam.yuk>
Re: Is zero even or odd? mmeron@cars3.uchicago.edu
Re: Is zero even or odd? <dak@gnu.org>
Re: Is zero even or odd? <dak@gnu.org>
Re: Is zero even or odd? <nospam@nospam.com>
Re: Is zero even or odd? <nospam@nospam.com>
Re: Is zero even or odd? <wyzelli@yahoo.com>
Re: Is zero even or odd? <salesEXTRACT@anasoft.co.uk>
Re: Is zero even or odd? <salesEXTRACT@anasoft.co.uk>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Tue, 21 Dec 2004 06:53:30 GMT
From: "John W. Krahn" <someone@example.com>
Subject: Re: change mac address formatting in a regex
Message-Id: <KLPxd.10434$dv1.632@edtnps89>
edward.nigma@gmail.com wrote:
> Good evening... I'm trying to construct a way to transform a mac
> address written in this format...
>
> 0:3:e2:12:4e:54
>
> To this:
>
> 0003E2124E54
>
> ...in a single regular expression. Actually the change in
> capitalization isn't very important, because I'm not sure if that can
> be done in the same regular expression that would also be adding
> additional zeros to the segments.
>
> I have different methods of doing this using loops that delimit the
> data already in place, but I now need to be able to do this through a
> single regular expression and it seems there should be a way!
$ perl -le'
$_ = q/0:3:e2:12:4e:54/;
print;
s/([[:xdigit:]]+|:)/ $1 eq ":" ? "" : sprintf "%02X", hex $1 /eg;
print;
'
0:3:e2:12:4e:54
0003E2124E54
John
--
use Perl;
program
fulfillment
------------------------------
Date: Tue, 21 Dec 2004 08:50:26 +0100
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: inserting a line into the body of an eMail before forwarding
Message-Id: <32q33aF3qa2c7U1@individual.net>
Lisa wrote:
> Gunnar Hjalmarsson wrote:
>>
>>> my $part = '(?:;\\s*charset=\\S+)?\\s+Cont\S+Encoding: *\\S+\\n';
>>
>> I've tweaked that row:
>>
>> my $part = '(?:;\s*charset=\S+)?\s+Cont\S+Encoding:\s\S+\n';
>>
>> Now, when I run the code below, it does insert "Original addressee:
>> ..." as expected.
>
> That was the fix right there!!
Hmm.. I missed a '*' character that should better be there:
my $part = '(?:;\s*charset=\S+)?\s+Cont\S+Encoding:\s*\S+\n';
---------------------------------------------------------^
I'm sure it can be further improved, but that's something to start with.
> thank you very much.
You're welcome. If you still wonder about details in the code, feel free
to ask. But first, please read about the s/// and qr// operators in
"perldoc perlop" and review "perldoc perlre".
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: Tue, 21 Dec 2004 05:15:26 GMT
From: "Gideon" <zerospam@yahoo.com>
Subject: Re: Is zero even or odd?
Message-Id: <OjOxd.7313$LW1.2398@fe2.columbus.rr.com>
I remember this as a homework problem in 9th grade algebra class many years
ago. More recently, my son encounted the same question in 7th grade algebra
class as an extra credit homework question. He did well but failed to realized
that one cannot just assume that zero must be even or odd but not both. Most
other students make the same mistake. The basic proof provided by many of us
in my algebra class is listed below:
--------
Homework question:
Is zero and even number or an odd number?
Math definitions:
Even numbers are numbers that can be written in the form 2n,
where n is an integer.
Odd numbers are numbers that can be written in the form 2n + 1,
where n is an integer.
First question and answer:
Is zero an even number?
That is: Is there an integer n, such that 0 = 2n ?
Yes. 0=2n => 0/2=n => 0=n (an obvious integer)
Therefore, 0 is an even number because if can satisfy the definition.
Second question and answer:
Is zero an odd number?
That is: Is there an integer n, such that 0 = 2n +1 ?
No. 0=2n+1 => -1=2n => -1/2=n which shows that n can not
be an integer in this case.
Therefore, 0 is not an odd number because it fails to satisfy the
definition.
--------
Any other math fact about even and odd numbers aren't needed to answer
the simple question "Is zero even, odd or both?" Of course, other facts about
even & odd numbers can be used to answer the question if those facts have
been rigorously proven. For example: A number is even if and only if it is the
sum of 2 even numbers.
Note that we cannot automatically assume that the set of even numbers and the
set of odd numbers are mutually exclusive just from the definitions above. Of
course, the proof of this fact is rather trivial:
x = 2n plus x=2m+1 =>
2n=2m+1 =>
2n/2 = 2m/2 +1/2 =>
n=m+1/2, which is impossible since n & m must both be integers
Based just upon the definitions, we also cannot make the assumption that every
integer must satisfy at least one of the definitions above and must therefore
be even or odd.
I point these out because the even/odd situation is an early introduction to
number theory and primative proofs for young students. And most students fall
into the trap of making assumptions which are not supported by the definitions
alone:
1) All even or odd numbers must be integers
2) All integers must be even or odd numbers
3) A number cannot be both even and odd
All three statements above are true but must be substantiated via proofs.
The debate over whether zero is positive or negative is also solved rather
quickly by reverting to the math definitions:
Positive numbers are numbers that are greater than zero.
Negative numbers are numbers that are less than zero.
------------------------------
Date: Tue, 21 Dec 2004 06:03:04 +0000 (UTC)
From: don@manx.misty.com (Don Klipstein)
Subject: Re: Is zero even or odd?
Message-Id: <slrncsff4o.t97.don@manx.misty.com>
In article <10sdnunotbnere2@corp.supernews.com>, Gactimus wrote:
>I know 0 is neither negative or positive but what about odd/even? I think
>it's even.
>
>Odd numbers start at 1 and go every other number 1,3,5,7;1,-1,-3,-5,-7
>Even starts at 2 and go every other number 2,4,6,8;2,0,-2,-4,-6,-8
Zero is definitely even. Dividing zero by 2 leaves no "remainder" or
"fraction".
However, as a bit of a digression, there are "odd functions" and "even
functions" - odd ones must have output zero when input is zero. Even
functions are permitted to have output zero or nonzero when input is
zero.
Functions can be odd, even or neither. With an even function, F(x) =
F(-x). With an odd function, F(-x) = -F(x).
- Don Klipstein (don@misty.com)
------------------------------
Date: Tue, 21 Dec 2004 07:08:09 GMT
From: "Kevin Aylward" <salesEXTRACT@anasoft.co.uk>
Subject: Re: Is zero even or odd?
Message-Id: <tZPxd.13524$ef5.10650@fe1.news.blueyonder.co.uk>
John Fields wrote:
> On Mon, 20 Dec 2004 09:21:25 -0600, John Sefton <john@petcom.com>
> wrote:
>
>
>> It's not a prime, because a prime can
>> only be divided by itself and 1.
>
> ---
> That's not true. A prime can be divided by anything, but an integer
> greater than one is prime if its only positive divisors are itself and
> one, but zero isn't prime because it's even.
> ---
>
>> 0 can't be divided by itself,
>
> ---
> Sure it can.
No it cant.
> Anything (or nothing) divided by itself = 1
O is specifically excluded from this result as dividing by zero causes
contradictions.
Division by zero is *defined* to be undefined. And my usual, "this is
not debatable" applies to this one. Read it up in any text book.
The limit:
L = f(x)/g(x) x->xo, where f(xo)=g(xo)=0
May or may not exist. If it dose, the limit may be any specific value
depending on the way the limit is approached.
In many case the *limit* represents physical reality. The notation 0/0
is a limit, and as such, is meaningless in mathematics.
Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
------------------------------
Date: Tue, 21 Dec 2004 07:08:11 GMT
From: "Kevin Aylward" <salesEXTRACT@anasoft.co.uk>
Subject: Re: Is zero even or odd?
Message-Id: <vZPxd.13525$ef5.3280@fe1.news.blueyonder.co.uk>
Fred Bloggs wrote:
> Alfred Z. Newmane wrote:
>> Nicholas O. Lindan wrote:
>>
>>> "John Sefton" <john@petcom.com> wrote
>>>
>>>
>>>> 0 can't be divided by itself,
>>>
>>> Sure it can: 0 / 0 = 0 * (1 / 0) = 0 * infinity = 1
>>>
>>> It works if the only three numbers in the universe are
>>> 0, 1, and infinity -- A number system that seems very
>>> suited to usenet.
>>
>>
>> Except for the fact that: 0 / 0 = undefined
>>
>> Or actually more correct: n / 0 = undefined
>>
>>
>
> 0/0={ SET OF ALL INTEGERS }
No.
>
> n/0= NULL SET for n<>0
>
> It is very well-defined.
No it isnt.
Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
------------------------------
Date: Tue, 21 Dec 2004 01:23:02 -0600
From: Bondo <bond@bondo.net>
Subject: Re: Is zero even or odd?
Message-Id: <41C7CF56.6E7CE8E0@bondo.net>
you can say that again! Hilarious!
"Nicholas O. Lindan" wrote:
> "John Sefton" <john@petcom.com> wrote
>
> > 0 can't be divided by itself,
>
> Sure it can: 0 / 0 = 0 * (1 / 0) = 0 * infinity = 1
>
> It works if the only three numbers in the universe are
> 0, 1, and infinity -- A number system that seems very
> suited to usenet.
>
> --
> Nicholas O. Lindan, Cleveland, Ohio
> Consulting Engineer: Electronics; Informatics; Photonics.
> Remove spaces etc. to reply: n o lindan at net com dot com
> psst.. want to buy an f-stop timer? nolindan.com/da/fstop/
------------------------------
Date: Tue, 21 Dec 2004 01:32:31 -0600
From: Bondo <bond@bondo.net>
Subject: Re: Is zero even or odd?
Message-Id: <41C7D18F.417653E7@bondo.net>
Nice statement. However, this 'proves' once again to me that I
was never any good at math because I'm nogood at thinking, just
too lazy! What a shame.
Bondo
Gideon wrote:
> I remember this as a homework problem in 9th grade algebra class many years
> ago. More recently, my son encounted the same question in 7th grade algebra
> class as an extra credit homework question. He did well but failed to realized
> that one cannot just assume that zero must be even or odd but not both. Most
> other students make the same mistake. The basic proof provided by many of us
> in my algebra class is listed below:
>
> --------
>
> Homework question:
> Is zero and even number or an odd number?
>
> Math definitions:
> Even numbers are numbers that can be written in the form 2n,
> where n is an integer.
> Odd numbers are numbers that can be written in the form 2n + 1,
> where n is an integer.
>
> First question and answer:
> Is zero an even number?
> That is: Is there an integer n, such that 0 = 2n ?
> Yes. 0=2n => 0/2=n => 0=n (an obvious integer)
> Therefore, 0 is an even number because if can satisfy the definition.
>
> Second question and answer:
> Is zero an odd number?
> That is: Is there an integer n, such that 0 = 2n +1 ?
> No. 0=2n+1 => -1=2n => -1/2=n which shows that n can not
> be an integer in this case.
> Therefore, 0 is not an odd number because it fails to satisfy the
> definition.
>
> --------
>
> Any other math fact about even and odd numbers aren't needed to answer
> the simple question "Is zero even, odd or both?" Of course, other facts about
> even & odd numbers can be used to answer the question if those facts have
> been rigorously proven. For example: A number is even if and only if it is the
> sum of 2 even numbers.
>
> Note that we cannot automatically assume that the set of even numbers and the
> set of odd numbers are mutually exclusive just from the definitions above. Of
> course, the proof of this fact is rather trivial:
> x = 2n plus x=2m+1 =>
> 2n=2m+1 =>
> 2n/2 = 2m/2 +1/2 =>
> n=m+1/2, which is impossible since n & m must both be integers
>
> Based just upon the definitions, we also cannot make the assumption that every
> integer must satisfy at least one of the definitions above and must therefore
> be even or odd.
>
> I point these out because the even/odd situation is an early introduction to
> number theory and primative proofs for young students. And most students fall
> into the trap of making assumptions which are not supported by the definitions
> alone:
> 1) All even or odd numbers must be integers
> 2) All integers must be even or odd numbers
> 3) A number cannot be both even and odd
>
> All three statements above are true but must be substantiated via proofs.
>
> The debate over whether zero is positive or negative is also solved rather
> quickly by reverting to the math definitions:
> Positive numbers are numbers that are greater than zero.
> Negative numbers are numbers that are less than zero.
------------------------------
Date: Tue, 21 Dec 2004 07:41:52 GMT
From: Ben Bradley <ben_nospam_bradley@mindspring.com>
Subject: Re: Is zero even or odd?
Message-Id: <2qkfs0hn09bcq36b02kgrp65no2g1cgoih@4ax.com>
In sci.math,
comp.soft-sys.matlab,
sci.physics,
alt.math.undergrad,
rec.puzzles,
sci.astro,
sci.electronics.design and
comp.lang.perl.misc, on Mon, 20 Dec 2004 21:02:32 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:
>I read in sci.electronics.design that David Kastrup <dak@gnu.org> wrote
>(in <x5mzw8k8f1.fsf@lola.goethe.zz>) about 'Is zero even or odd?', on
>Mon, 20 Dec 2004:
>
>>Ah, so 1 = 0/0 = (0+0)/0 = (0/0) + (0/0) = 2 ?
>
>0/0 can take ANY value.
Furthermore, 0/0 can GIVE any value. What a versatile expression!
-----
http://mindspring.com/~benbradley
------------------------------
Date: Tue, 21 Dec 2004 08:45:16 +0100
From: Josef Moellers <josef.moellers@fujitsu-siemens.com>
Subject: Re: Is zero even or odd?
Message-Id: <cq8k5q$vk3$1@nntp.fujitsu-siemens.com>
Nicholas O. Lindan wrote:
> "John Sefton" <john@petcom.com> wrote
>=20
>=20
>>0 can't be divided by itself,
>=20
>=20
> Sure it can: 0 / 0 =3D 0 * (1 / 0) =3D 0 * infinity =3D 1
>=20
> It works if the only three numbers in the universe are
> 0, 1, and infinity -- A number system that seems very
> suited to usenet.
>=20
Not only usenet: someone once postulated that the only three "values" to =
be used in providing computer resources should be 0, 1 and infinity=20
(which he meant to mean "unlimited" (for all practical purposes) (*)).
(*) My math teacher always said "A sphere's surface is unlimited but not =
infinite", just to highlight the difference between the two.
--=20
Josef M=F6llers (Pinguinpfleger bei FSC)
If failure had no penalty success would not be a prize
-- T. Pratchett
------------------------------
Date: Tue, 21 Dec 2004 09:05:16 GMT
From: mmeron@cars3.uchicago.edu
Subject: Re: Is zero even or odd?
Message-Id: <gHRxd.11$35.4404@news.uchicago.edu>
In article <kSDxd.34179$jf5.6646@fe1.texas.rr.com>, "Morituri-|-Max" <newage@sendarico.net> writes:
>Gactimus wrote:
>> I know 0 is neither negative or positive but what about odd/even? I think
>> it's even.
>
>It's a placeholder you twit.
>
It is a valid number. And it is even.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
------------------------------
Date: Tue, 21 Dec 2004 09:00:52 +0000
From: John Woodgate <jmw@jmwa.demon.contraspam.yuk>
Subject: Re: Is zero even or odd?
Message-Id: <rsFftSDEZ+xBFwx3@jmwa.demon.co.uk>
I read in sci.electronics.design that Clifford Heath <no@spam.please>
wrote (in <32pkemF3p3b5bU1@individual.net>) about 'Is zero even or
odd?', on Tue, 21 Dec 2004:
>John Woodgate wrote:
>>>>Lim{x->0}[(-x^)2] = 0
>>>Either you mangled your parentheses, or this is a insidious way of
>>>sneaking in a smilie.
>> Nothing is mangled if you view plain text.
>
>Perhaps you could explain what (-x^)2 means then?
How did you manage to move the ^? (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
------------------------------
Date: Tue, 21 Dec 2004 09:19:21 GMT
From: mmeron@cars3.uchicago.edu
Subject: Re: Is zero even or odd?
Message-Id: <tURxd.14$35.4459@news.uchicago.edu>
In article <32p53dF3paevvU1@individual.net>, "Alfred Z. Newmane" <a.newmane.remove@eastcoastcz.com> writes:
>Nicholas O. Lindan wrote:
>> "John Sefton" <john@petcom.com> wrote
>>
>>> 0 can't be divided by itself,
>>
>> Sure it can: 0 / 0 = 0 * (1 / 0) = 0 * infinity = 1
>>
>> It works if the only three numbers in the universe are
>> 0, 1, and infinity -- A number system that seems very
>> suited to usenet.
>
>Except for the fact that: 0 / 0 = undefined
>
>Or actually more correct: n / 0 = undefined
>
The two are not the same.
The definition of the ratio a/b is
a/b = r iff b*r = a
for the case of n/0 there is no r such that r*0 = n (follows from the
definition of zero. Therefore n/0 (for non zero n) *does not exist*.
On the other hand, for 0/0, every r qualifies since for every r, r*0 =
0 (the definition of zero, again). Therefore, 0/0 is truly undefined,
in the sense that it is impossible to *uniquely* assign a value to the
ratio r.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
------------------------------
Date: Tue, 21 Dec 2004 11:30:37 +0100
From: David Kastrup <dak@gnu.org>
Subject: Re: Is zero even or odd?
Message-Id: <x5r7lkosdu.fsf@lola.goethe.zz>
Fred Bloggs <nospam@nospam.com> writes:
> Alfred Z. Newmane wrote:
>> Nicholas O. Lindan wrote:
>>
>>>"John Sefton" <john@petcom.com> wrote
>>>
>>>
>>>>0 can't be divided by itself,
>>>
>>>Sure it can: 0 / 0 = 0 * (1 / 0) = 0 * infinity = 1
>>>
>>>It works if the only three numbers in the universe are
>>>0, 1, and infinity -- A number system that seems very
>>>suited to usenet.
>> Except for the fact that: 0 / 0 = undefined
>> Or actually more correct: n / 0 = undefined
>>
>
> 0/0={ SET OF ALL INTEGERS }
>
> n/0= NULL SET for n<>0
>
> It is very well-defined.
So { SET OF ALL INTEGERS } = 0/0 = (0+0)/0 = (2*0)/0 = 2*(0/0)
= 2* {SET OF ALL INTEGERS } = {SET OF ALL EVEN INTEGERS}?
Odd.
--
David Kastrup, Kriemhildstr. 15, 44793 Bochum
------------------------------
Date: Tue, 21 Dec 2004 11:36:05 +0100
From: David Kastrup <dak@gnu.org>
Subject: Re: Is zero even or odd?
Message-Id: <x5mzw8os4q.fsf@lola.goethe.zz>
"Kevin Aylward" <salesEXTRACT@anasoft.co.uk> writes:
> The limit:
>
> L = f(x)/g(x) x->xo, where f(xo)=g(xo)=0
>
> May or may not exist. If it dose, the limit may be any specific value
> depending on the way the limit is approached.
>
> In many case the *limit* represents physical reality. The notation
> 0/0 is a limit, and as such, is meaningless in mathematics.
Hogwash. The notation 0/0 is most certainly not a limit, like 4/2 is
not a limit. And how could you define a limit if there were no
function values to start with?
0/0 is clearly, if anything, a constant expression. And it turns out
that its value is undefined. And limits have nothing to do with that.
There are "limits of the form 0/0", but this is a shorthand for
something completely different, and such limits in general _have_ a
value (depending on just what is taken to the limit here).
--
David Kastrup, Kriemhildstr. 15, 44793 Bochum
------------------------------
Date: Tue, 21 Dec 2004 10:37:35 GMT
From: Fred Bloggs <nospam@nospam.com>
Subject: Re: Is zero even or odd?
Message-Id: <41C7FC91.7000801@nospam.com>
Kevin Aylward wrote:
> Fred Bloggs wrote:
>
>>Alfred Z. Newmane wrote:
>>
>>>Nicholas O. Lindan wrote:
>>>
>>>
>>>>"John Sefton" <john@petcom.com> wrote
>>>>
>>>>
>>>>
>>>>>0 can't be divided by itself,
>>>>
>>>>Sure it can: 0 / 0 = 0 * (1 / 0) = 0 * infinity = 1
>>>>
>>>>It works if the only three numbers in the universe are
>>>>0, 1, and infinity -- A number system that seems very
>>>>suited to usenet.
>>>
>>>
>>>Except for the fact that: 0 / 0 = undefined
>>>
>>>Or actually more correct: n / 0 = undefined
>>>
>>>
>>
>>0/0={ SET OF ALL INTEGERS }
>
>
> No.
>
>
>>n/0= NULL SET for n<>0
>>
>>It is very well-defined.
>
>
> No it isnt.
>
> Kevin Aylward
You apparently have stumbled on something else you know damn little
about. In case you need help with this , you might note that "/" is NOT
an operator on the integers, it is the "inverse" of a multiplication
operator. Inverse is a well-defined concept but not necessarily a
function, it is a set theoretic mapping. E.G. m/n={ q: m=q*n} by
definition, so that m/n which is actually a set which can be empty, a
singleton, or infinite. In the case of m/n, it is then m/n = F^-1(m)
where F(x)= n*x. Your reasoning would lead one to believe /: I x I -> I
is a function, which it isn't.
------------------------------
Date: Tue, 21 Dec 2004 10:40:32 GMT
From: Fred Bloggs <nospam@nospam.com>
Subject: Re: Is zero even or odd?
Message-Id: <41C7FD4F.3060902@nospam.com>
David Kastrup wrote:
> Fred Bloggs <nospam@nospam.com> writes:
>
>
>>Alfred Z. Newmane wrote:
>>
>>>Nicholas O. Lindan wrote:
>>>
>>>
>>>>"John Sefton" <john@petcom.com> wrote
>>>>
>>>>
>>>>
>>>>>0 can't be divided by itself,
>>>>
>>>>Sure it can: 0 / 0 = 0 * (1 / 0) = 0 * infinity = 1
>>>>
>>>>It works if the only three numbers in the universe are
>>>>0, 1, and infinity -- A number system that seems very
>>>>suited to usenet.
>>>
>>>Except for the fact that: 0 / 0 = undefined
>>>Or actually more correct: n / 0 = undefined
>>>
>>
>>0/0={ SET OF ALL INTEGERS }
>>
>>n/0= NULL SET for n<>0
>>
>>It is very well-defined.
>
>
> So { SET OF ALL INTEGERS } = 0/0 = (0+0)/0 = (2*0)/0 = 2*(0/0)
> = 2* {SET OF ALL INTEGERS } = {SET OF ALL EVEN INTEGERS}?
>
> Odd.
>
Wrong- where do you get off saying (2*0)/0= 2*(0/0) ?
------------------------------
Date: Tue, 21 Dec 2004 10:40:11 GMT
From: "Peter Wyzl" <wyzelli@yahoo.com>
Subject: Re: Is zero even or odd?
Message-Id: <f4Txd.83068$K7.7863@news-server.bigpond.net.au>
"Gactimus" <gactimus@xrs.net> wrote in message
news:10sdnunotbnere2@corp.supernews.com...
:I know 0 is neither negative or positive but what about odd/even? I think
: it's even.
:
: Odd numbers start at 1 and go every other number 1,3,5,7;1,-1,-3,-5,-7
: Even starts at 2 and go every other number 2,4,6,8;2,0,-2,-4,-6,-8
I think it's odd that you even need to ask...
--
Wyzelli
more into words than numbers...
------------------------------
Date: Tue, 21 Dec 2004 11:03:41 GMT
From: "Kevin Aylward" <salesEXTRACT@anasoft.co.uk>
Subject: Re: Is zero even or odd?
Message-Id: <hqTxd.17008$ef5.10156@fe1.news.blueyonder.co.uk>
David Kastrup wrote:
> "Kevin Aylward" <salesEXTRACT@anasoft.co.uk> writes:
>
>> The limit:
>>
>> L = f(x)/g(x) x->xo, where f(xo)=g(xo)=0
>>
>> May or may not exist. If it dose, the limit may be any specific value
>> depending on the way the limit is approached.
I should clarify this. This is referring to the notion that different
f(x) and g(x) will lead to different limits. Usually for the limit to
have meaning, it must be the same independent of the way a specific f(x)
and g(x) approaches the limit.
>>
>> In many case the *limit* represents physical reality. The notation
>> 0/0 is a limit, and as such, is meaningless in mathematics.
>
> Hogwash. The notation 0/0 is most certainly not a limit, like 4/2 is
This was a typo, for which I apologise. It should have been abundantly
clear from the context that I was saying "is not a limit". Unfortunately
when I spell checked I inadvertently deleted a word.
The above wouldn't make logical sense at all otherwise, as I already
defined "L" a limit, and distinguished it from 0/0. How can a limit be
physically meaningfull, yet meaningless?
> not a limit. And how could you define a limit if there were no
> function values to start with?
>
> 0/0 is clearly, if anything, a constant expression. And it turns out
> that its value is undefined.
Which is what I said i.e. "0/0 is meaningless"
Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
------------------------------
Date: Tue, 21 Dec 2004 11:04:59 GMT
From: "Kevin Aylward" <salesEXTRACT@anasoft.co.uk>
Subject: Re: Is zero even or odd?
Message-Id: <vrTxd.17025$ef5.8688@fe1.news.blueyonder.co.uk>
Fred Bloggs wrote:
> Kevin Aylward wrote:
>> Fred Bloggs wrote:
>>
>>> Alfred Z. Newmane wrote:
>>>
>>>> Nicholas O. Lindan wrote:
>>>>
>>>>
>>>>> "John Sefton" <john@petcom.com> wrote
>>>>>
>>>>>
>>>>>
>>>>>> 0 can't be divided by itself,
>>>>>
>>>>> Sure it can: 0 / 0 = 0 * (1 / 0) = 0 * infinity = 1
>>>>>
>>>>> It works if the only three numbers in the universe are
>>>>> 0, 1, and infinity -- A number system that seems very
>>>>> suited to usenet.
>>>>
>>>>
>>>> Except for the fact that: 0 / 0 = undefined
>>>>
>>>> Or actually more correct: n / 0 = undefined
>>>>
>>>>
>>>
>>> 0/0={ SET OF ALL INTEGERS }
>>
>>
>> No.
>>
>>
>>> n/0= NULL SET for n<>0
>>>
>>> It is very well-defined.
>>
>>
>> No it isnt.
>>
>> Kevin Aylward
>
> You apparently have stumbled on something else you know damn little
> about.
There is a lot I don't know, but this isn't an example of such.
>In case you need help with this , you might note that "/" is
> NOT an operator on the integers,
No it isn't, it is an operator on all numbers, integer or otherwise.
>it is the "inverse" of a
> multiplication operator.
Sure, you can have *another* meaning to the / operator in a different
context, but this aint that context. This discussion is about a/b as
usually understood in arithmetic.
>Inverse is a well-defined concept but not
> necessarily a function, it is a set theoretic mapping. E.G. m/n={ q:
> m=q*n} by definition, so that m/n which is actually a set which can
> be empty, a singleton, or infinite.
My, my, aint you a clever dude...
>In the case of m/n, it is then
> m/n = F^-1(m) where F(x)= n*x. Your reasoning would lead one to
> believe /: I x I -> I is a function, which it isn't.
Nope. I am using a well understood definition of division as applicable
to this argument.
Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
------------------------------
Date: 21 Dec 2004 08:22:48 GMT
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.5 $)
Message-Id: <41c7dd57$0$29679$8b463f8a@news.nationwide.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.5 $)
This newsgroup, commonly called clpmisc, is a technical newsgroup
intended to be used for discussion of Perl related issues (except job
postings), whether it be comments or questions.
As you would expect, clpmisc discussions are usually very technical in
nature and there are conventions for conduct in technical newsgroups
going somewhat beyond those in non-technical newsgroups.
The article at:
http://www.catb.org/~esr/faqs/smart-questions.html
describes how to get answers from technical people in general.
This article describes things that you should, and should not, do to
increase your chances of getting an answer to your Perl question. It is
available in POD, HTML and plain text formats at:
http://mail.augustmail.com/~tadmc/clpmisc.shtml
For more information about netiquette in general, see the "Netiquette
Guidelines" at:
http://andrew2.andrew.cmu.edu/rfc/rfc1855.html
A note to newsgroup "regulars":
Do not use these guidelines as a "license to flame" or other
meanness. It is possible that a poster is unaware of things
discussed here. Give them the benefit of the doubt, and just
help them learn how to post, rather than assume
A note about technical terms used here:
In this document, we use words like "must" and "should" as
they're used in technical conversation (such as you will
encounter in this newsgroup). When we say that you *must* do
something, we mean that if you don't do that something, then
it's unlikely that you will benefit much from this group.
We're not bossing you around; we're making the point without
lots of words.
Do *NOT* send email to the maintainer of these guidelines. It will be
discarded unread. The guidelines belong to the newsgroup so all
discussion should appear in the newsgroup. I am just the secretary that
writes down the consensus of the group.
Before posting to comp.lang.perl.misc
Must
This section describes things that you *must* do before posting to
clpmisc, in order to maximize your chances of getting meaningful replies
to your inquiry and to avoid getting flamed for being lazy and trying to
have others do your work.
The perl distribution includes documentation that is copied to your hard
drive when you install perl. Also installed is a program for looking
things up in that (and other) documentation named 'perldoc'.
You should either find out where the docs got installed on your system,
or use perldoc to find them for you. Type "perldoc perldoc" to learn how
to use perldoc itself. Type "perldoc perl" to start reading Perl's
standard documentation.
Check the Perl Frequently Asked Questions (FAQ)
Checking the FAQ before posting is required in Big 8 newsgroups in
general, there is nothing clpmisc-specific about this requirement.
You are expected to do this in nearly all newsgroups.
You can use the "-q" switch with perldoc to do a word search of the
questions in the Perl FAQs.
Check the other standard Perl docs (*.pod)
The perl distribution comes with much more documentation than is
available for most other newsgroups, so in clpmisc you should also
see if you can find an answer in the other (non-FAQ) standard docs
before posting.
It is *not* required, or even expected, that you actually *read* all of
Perl's standard docs, only that you spend a few minutes searching them
before posting.
Try doing a word-search in the standard docs for some words/phrases
taken from your problem statement or from your very carefully worded
"Subject:" header.
Really Really Should
This section describes things that you *really should* do before posting
to clpmisc.
Lurk for a while before posting
This is very important and expected in all newsgroups. Lurking means
to monitor a newsgroup for a period to become familiar with local
customs. Each newsgroup has specific customs and rituals. Knowing
these before you participate will help avoid embarrassing social
situations. Consider yourself to be a foreigner at first!
Search a Usenet archive
There are tens of thousands of Perl programmers. It is very likely
that your question has already been asked (and answered). See if you
can find where it has already been answered.
One such searchable archive is:
http://groups.google.com/advanced_group_search
If You Like
This section describes things that you *can* do before posting to
clpmisc.
Check Other Resources
You may want to check in books or on web sites to see if you can
find the answer to your question.
But you need to consider the source of such information: there are a
lot of very poor Perl books and web sites, and several good ones
too, of course.
Posting to comp.lang.perl.misc
There can be 200 messages in clpmisc in a single day. Nobody is going to
read every article. They must decide somehow which articles they are
going to read, and which they will skip.
Your post is in competition with 199 other posts. You need to "win"
before a person who can help you will even read your question.
These sections describe how you can help keep your article from being
one of the "skipped" ones.
Is there a better place to ask your question?
Question should be about Perl, not about the application area
It can be difficult to separate out where your problem really is,
but you should make a conscious effort to post to the most
applicable newsgroup. That is, after all, where you are the most
likely to find the people who know how to answer your question.
Being able to "partition" a problem is an essential skill for
effectively troubleshooting programming problems. If you don't get
that right, you end up looking for answers in the wrong places.
It should be understood that you may not know that the root of your
problem is not Perl-related (the two most frequent ones are CGI and
Operating System related), so off-topic postings will happen from
time to time. Be gracious when someone helps you find a better place
to ask your question by pointing you to a more applicable newsgroup.
How to participate (post) in the clpmisc community
Carefully choose the contents of your Subject header
You have 40 precious characters of Subject to win out and be one of
the posts that gets read. Don't waste them. Take care while
composing them, they are the key that opens the door to getting an
answer.
Spend them indicating what aspect of Perl others will find if they
should decide to read your article.
Do not spend them indicating "experience level" (guru, newbie...).
Do not spend them pleading (please read, urgent, help!...).
Do not spend them on non-Subjects (Perl question, one-word
Subject...)
For more information on choosing a Subject see "Choosing Good
Subject Lines":
http://www.cpan.org/authors/id/D/DM/DMR/subjects.post
Part of the beauty of newsgroup dynamics, is that you can contribute
to the community with your very first post! If your choice of
Subject leads a fellow Perler to find the thread you are starting,
then even asking a question helps us all.
Use an effective followup style
When composing a followup, quote only enough text to establish the
context for the comments that you will add. Always indicate who
wrote the quoted material. Never quote an entire article. Never
quote a .signature (unless that is what you are commenting on).
Intersperse your comments *following* each section of quoted text to
which they relate. Unappreciated followup styles are referred to as
"top-posting", "Jeopardy" (because the answer comes before the
question), or "TOFU" (Text Over, Fullquote Under).
Reversing the chronology of the dialog makes it much harder to
understand (some folks won't even read it if written in that style).
For more information on quoting style, see:
http://web.presby.edu/~nnqadmin/nnq/nquote.html
Speak Perl rather than English, when possible
Perl is much more precise than natural language. Saying it in Perl
instead will avoid misunderstanding your question or problem.
Do not say: I have variable with "foo\tbar" in it.
Instead say: I have $var = "foo\tbar", or I have $var = 'foo\tbar',
or I have $var = <DATA> (and show the data line).
Ask perl to help you
You can ask perl itself to help you find common programming mistakes
by doing two things: enable warnings (perldoc warnings) and enable
"strict"ures (perldoc strict).
You should not bother the hundreds/thousands of readers of the
newsgroup without first seeing if a machine can help you find your
problem. It is demeaning to be asked to do the work of a machine. It
will annoy the readers of your article.
You can look up any of the messages that perl might issue to find
out what the message means and how to resolve the potential mistake
(perldoc perldiag). If you would like perl to look them up for you,
you can put "use diagnostics;" near the top of your program.
Do not re-type Perl code
Use copy/paste or your editor's "import" function rather than
attempting to type in your code. If you make a typo you will get
followups about your typos instead of about the question you are
trying to get answered.
Provide enough information
If you do the things in this item, you will have an Extremely Good
chance of getting people to try and help you with your problem!
These features are a really big bonus toward your question winning
out over all of the other posts that you are competing with.
First make a short (less than 20-30 lines) and *complete* program
that illustrates the problem you are having. People should be able
to run your program by copy/pasting the code from your article. (You
will find that doing this step very often reveals your problem
directly. Leading to an answer much more quickly and reliably than
posting to Usenet.)
Describe *precisely* the input to your program. Also provide example
input data for your program. If you need to show file input, use the
__DATA__ token (perldata.pod) to provide the file contents inside of
your Perl program.
Show the output (including the verbatim text of any messages) of
your program.
Describe how you want the output to be different from what you are
getting.
If you have no idea at all of how to code up your situation, be sure
to at least describe the 2 things that you *do* know: input and
desired output.
Do not provide too much information
Do not just post your entire program for debugging. Most especially
do not post someone *else's* entire program.
Do not post binaries, HTML, or MIME
clpmisc is a text only newsgroup. If you have images or binaries
that explain your question, put them in a publically accessible
place (like a Web server) and provide a pointer to that location. If
you include code, cut and paste it directly in the message body.
Don't attach anything to the message. Don't post vcards or HTML.
Many people (and even some Usenet servers) will automatically filter
out such messages. Many people will not be able to easily read your
post. Plain text is something everyone can read.
Social faux pas to avoid
The first two below are symptoms of lots of FAQ asking here in clpmisc.
It happens so often that folks will assume that it is happening yet
again. If you have looked but not found, or found but didn't understand
the docs, say so in your article.
Asking a Frequently Asked Question
It should be understood that you may have missed the applicable FAQ
when you checked, which is not a big deal. But if the Frequently
Asked Question is worded similar to your question, folks will assume
that you did not look at all. Don't become indignant at pointers to
the FAQ, particularly if it solves your problem.
Asking a question easily answered by a cursory doc search
If folks think you have not even tried the obvious step of reading
the docs applicable to your problem, they are likely to become
annoyed.
If you are flamed for not checking when you *did* check, then just
shrug it off (and take the answer that you got).
Asking for emailed answers
Emailed answers benefit one person. Posted answers benefit the
entire community. If folks can take the time to answer your
question, then you can take the time to go get the answer in the
same place where you asked the question.
It is OK to ask for a *copy* of the answer to be emailed, but many
will ignore such requests anyway. If you munge your address, you
should never expect (or ask) to get email in response to a Usenet
post.
Ask the question here, get the answer here (maybe).
Beware of saying "doesn't work"
This is a "red flag" phrase. If you find yourself writing that,
pause and see if you can't describe what is not working without
saying "doesn't work". That is, describe how it is not what you
want.
Sending a "stealth" Cc copy
A "stealth Cc" is when you both email and post a reply without
indicating *in the body* that you are doing so.
Be extra cautious when you get upset
Count to ten before composing a followup when you are upset
This is recommended in all Usenet newsgroups. Here in clpmisc, most
flaming sub-threads are not about any feature of Perl at all! They
are most often for what was seen as a breach of netiquette. If you
have lurked for a bit, then you will know what is expected and won't
make such posts in the first place.
But if you get upset, wait a while before writing your followup. I
recommend waiting at least 30 minutes.
Count to ten after composing and before posting when you are upset
After you have written your followup, wait *another* 30 minutes
before committing yourself by posting it. You cannot take it back
once it has been said.
AUTHOR
Tad McClellan <tadmc@augustmail.com> and many others on the
comp.lang.perl.misc newsgroup.
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
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------------------------------
End of Perl-Users Digest V10 Issue 7546
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