Mersenne Digest      Wednesday, February 9 2000      Volume 01 : Number 691




----------------------------------------------------------------------

Date: Wed, 9 Feb 2000 10:28:25 -0600 
From: Jeremy Blosser <[EMAIL PROTECTED]>
Subject: RE: Mersenne: pi

Actually bro, I highly doubt the Universe is spherical. If one is to believe
in the concept of gravity bending space-time, then the Universe would be
more akin to some bubbly, blobby, amorphous structure (see
http://www.sciam.com/1999/0699issue/0699landy.html)

Interestingly enough, you could conceptually have "bubbles" in space-time
which are cut off from the rest of the universe.

Anyway, back to Pi... I think that the major issue is that we look at a
circle and think of some number of units, atoms, particles, whatever...
However, we neglect the fact that a circle isn't constituted of particles...
This seems to been some weird human characteristic, we think of everything
in units (time for example)...

Take the function y=x, there are an infinite number of points on that
line... Even, if I limit the range of x from (-1,1), there are still an
infinite number of points on that line... So even the simple function y=x
has infinite precision, yet I can precisely determine that the length of
that line is 2*sqrt(2).

- -----Original Message-----
From: Aaron Blosser [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, February 09, 2000 8:41 AM
To: Mersenne@Base. Com
Subject: RE: Mersenne: pi


> The problem isn't that Pi isn't finite, it's less than 4 so it's finite.
> The problem isn't that it isn't exact.
> The problem is that it can't be represented exactly in decimals which mens
> that when we write the expansion, we'll always have to make do with an
> approximation to the exact value.

Consider this:

Let's assume that the universe is spherical (a logical assumption if we
assume it's the result of a currently expanding explosion xx years ago).

If we were to calculate the radius of this sphere down to a single atomic
width, using some decently expanded version of pi would could come up with
an exact number for the volume of the universe.

What I'm getting at is that at some point, pi reaches a practical limit at
which expanding more decimal points is an abstraction because we could never
measure anything large enough for it to be useful.  I mean, c'mon!  The
universe is only so big! :-)

Being in a hurry, I don't have the time to figure out how many decimal
places that would be...perhaps someone more adventurous would care to give
it a go.

Aaron

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------------------------------

Date: Wed, 9 Feb 2000 12:00:26 EST
From: [EMAIL PROTECTED]
Subject: Mersenne: Re: Mersenne : pi

> Date: Wed, 09 Feb 2000 10:50:44 -0500
>  From: Jeff Woods <[EMAIL PROTECTED]>
>  Subject: Re: Mersenne: pi
>  
>  You're bumping up against the Fundamental Theorem of Calculus here.   Pi 
>  DOES have a precisely defined value, but you cannot express it in decimal 
>  form.  You can express it as an infinite expansion, however.
>  
>  Just as you can never get to the end of pi, though its value is known, you 
>  can never PRECISELY note the area of a circle -- you can only express it 
>  more and more accurately, depending on how accurate the value of PI you 
use 
> is.

Actually what you're saying is, you can PRECISELY know the area of a circle, 
or PRECISELY know the diameter of a circle, but not both, without resorting 
to using the symbol pi. Sounds like an instance of the Pisenberg Uncertainty 
Principle to me....

Well, back to lurking.
Phil Brady
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------------------------------

Date: Wed, 09 Feb 2000 14:45:44 -0500
From: Bassam Abdul-Baki <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Re: Mersenne : pi

Actually, you can express PI in heaxadecimal form.  This was proven by Simon
Plouffe.  A decimal expression is still unknown.

Bassam Abdul-Baki

[EMAIL PROTECTED] wrote:

> > Date: Wed, 09 Feb 2000 10:50:44 -0500
> >  From: Jeff Woods <[EMAIL PROTECTED]>
> >  Subject: Re: Mersenne: pi
> >
> >  You're bumping up against the Fundamental Theorem of Calculus here.   Pi
> >  DOES have a precisely defined value, but you cannot express it in decimal
> >  form.  You can express it as an infinite expansion, however.
> >
> >  Just as you can never get to the end of pi, though its value is known, you
> >  can never PRECISELY note the area of a circle -- you can only express it
> >  more and more accurately, depending on how accurate the value of PI you
> use
> > is.
>
> Actually what you're saying is, you can PRECISELY know the area of a circle,
> or PRECISELY know the diameter of a circle, but not both, without resorting
> to using the symbol pi. Sounds like an instance of the Pisenberg Uncertainty
> Principle to me....
>
> Well, back to lurking.
> Phil Brady
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------------------------------

Date: Wed, 9 Feb 2000 15:36:12 EST
From: [EMAIL PROTECTED]
Subject: Mersenne: Re: optimizing for Athlon

Brian Beesley wrote:

>The optimization that should probably be done for Athlon is to 
>organize the code to allow FMUL & FADD to execute in parallel (which 
>the Pentium II/III core just can't manage). This could give a speedup 
>of the order of 40%.

That would be nice if true, but I suspect it's a bit overoptimistic.
The reason is this: the Athlon utilizes out-of-order execution, i.e.
even if the assembly code indicates a certain instruction ordering
(e.g. FADDs interleaved with FMULs, as required for the Pentium, which
can complete just one double-precision floating op per cycle), the CPU
is free to execute them in a different order, as long as any data
dependencies are preserved. That means the Athlon is probably already
executing quite a few such FADD/FMUL pairs in parallel, unless I'm
misunstanding something fundamental about its OOE capabilities.

As I've found the available Athlon documentation (the technical brief
and the code optimization guide from the AMD website) to be frustratingly
vague about things like the register set architecture and the functional
units, can anyone answer the following for me?

1a,b,c) How many floating-point registers does the Athlon have? Are these
all 80 bits? Are they accessed via the same kind of stack-based model as
the Pentium?

2a,b,c) I believe the Athlon has two floating adders in addition to a floating
multiplier. Can it dispatch 2 FADDs and 1 FMUL per cycle? Can it do 2 double-
precision FADDs per cycle, or just do single-precision adds in parallel?
(The former would help with the higher-radix FFTs in an LL code, since these
have more adds than multiplies, but the latter, while nice for multimedia
applications, would be useless for speeding LL testing.)

Thanks,
- -Ernst

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------------------------------

Date: Wed, 9 Feb 2000 15:35:44 -0500
From: "Frank_A_L_I_N_Y" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: pi

>Can we say the same to the case of 10 divide by 3 , The result is 3 1/3 but
>as a decimal way of writing you never end.
  Almost, but the difference is 10 / 3 is expressable as one number divided
by another.
 to my kowledge there is no a and b where a/b=pi.

 Someone correct me if I am wrong.

- -----Original Message-----
From: Grieken, Paul van <[EMAIL PROTECTED]>
To: 'Jud McCranie' <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Wednesday, February 09, 2000 11:53 AM
Subject: RE: Mersenne: pi


>I am not a math man but I follow this discussion.
>Can we say the same to the case of 10 divide by 3 , The result is 3 1/3 but
>as a decimal way of writing you never end.
>
>Maybe I just miss the whole thing, in that case I am sorry, and will
>continue just reading this kind of topics.
>
>Bye,
>Paul van Grieken
>
>> -----Original Message-----
>> From: Jud McCranie [SMTP:[EMAIL PROTECTED]]
>> Sent: Wednesday, February 09, 2000 3:22 PM
>> To: [EMAIL PROTECTED]
>> Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]
>> Subject: Re: Mersenne: pi
>>
>> At 12:06 AM 2/9/00 -0600, [EMAIL PROTECTED] wrote:
>>
>>  >But when I look at a circle I see a finite area within the circle with
>> no
>> >means of growing or escape.  Logic seems to indicate that pi would have
>> to
>> >be a finite exact value since the area in the circle is finite.
>>
>> No, pi is irrational, which means that the digits go on forever without
>> repeating.
>>
>>
>> >So, either the figure for pi is in error (not likely) or pi has a end.
>>
>> The calculated value of pi is never exact, since it is calculated to a
>> finite precision.
>>
>>
>> +--------------------------------------------------------+
>> |                  Jud McCranie                          |
>> |                                                        |
>> | 137*2^197783+1 is prime!  (59,541 digits, 11/11/99)    |
>> | 137*2^224879+1 is prime!  (67,687 digits, 1/00)        |
>> +--------------------------------------------------------+
>>
>> _________________________________________________________________
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>_________________________________________________________________
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------------------------------

Date: Wed, 09 Feb 2000 12:53:01 -0800
From: Michael Gebis <[EMAIL PROTECTED]>
Subject: Re: Mersenne: pi 

>>>>> "Aaron" == Aaron Blosser <[EMAIL PROTECTED]>
>>>>> wrote the following on Wed, 9 Feb 2000 07:40:37 -0700

  Aaron> If we were to calculate the radius of this sphere down to a
  Aaron> single atomic width, using some decently expanded version of
  Aaron> pi would could come up with an exact number for the volume of
  Aaron> the universe.

  Aaron> What I'm getting at is that at some point, pi reaches a
  Aaron> practical limit at which expanding more decimal points is an
  Aaron> abstraction because we could never measure anything large
  Aaron> enough for it to be useful.  I mean, c'mon!  The universe is
  Aaron> only so big! :-)

  Aaron> Being in a hurry, I don't have the time to figure out how
  Aaron> many decimal places that would be...perhaps someone more
  Aaron> adventurous would care to give it a go.

Cecil Adams mentioned this in one of his columns a few years ago; you
can find a copy online at:

  http://www.straightdope.com/classics/a3_357.html

Cecil's column is intended for the general public, not those trained
in mathematics, so it's a good "everybody can understand" discussion.

Executive summary:
  Pi to 35 decimal places lets you compute the circumference of the universe
  with an error of less than the radius of a hydrogen atom.
  Pi to 39 decimal places lets you compute the circumference of the universe
  with an error of less than the radius of the NUCLEUS of a hydrogen atom.

Mike

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------------------------------

Date: Thu, 10 Feb 2000 10:32:22 +1300 (NZDT)
From: Bill Rea <[EMAIL PROTECTED]>
Subject: Re: Mersenne: PrimeNet Top Producers List

Scott wrote:-

>Following the database synchro we performed on PrimeNet yesterday, we
>cleaned up some of the 'dead' user accounts over a year old.  The
>cumulative machine times were added to the Entropia.com, Inc.
>'challenge' account, the first one opened on PrimeNet in April 1997.
>Hopefully nobody will mind our reclaiming the fragmented time.  :-)

Do people using the manual check out forms get in the Top Producers
list? I ask because I've never been able to find myself in the list
and I had an email from a former GIMPS contributor who claimed he
got no credit for exponents tested through the manual check out/check in
pages.

Bill Rea, Information Technology Services, University of Canterbury  \_ 
E-Mail b dot rea at its dot canterbury dot ac dot nz                 </   New 
Phone   64-3-364-2331, Fax     64-3-364-2332                        /)  Zealand 
Unix Systems Administrator                                         (/' 
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------------------------------

Date: Wed, 9 Feb 2000 16:39:07 -0500 (EST)
From: Jason Stratos Papadopoulos <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Re: optimizing for Athlon

On Wed, 9 Feb 2000 [EMAIL PROTECTED] wrote:

> As I've found the available Athlon documentation (the technical brief
> and the code optimization guide from the AMD website) to be frustratingly
> vague about things like the register set architecture and the functional
> units, can anyone answer the following for me?

That's putting it kindly. AMD's Athlon optimization manual sucks bigtime.
They forget to list the actual freakin' latencies of *any* instructions,
but remember to point out the "industry-leading" and "industry-standard"
features of the chip. I hope I never see these two terms in a technical
manual again.

> 1a,b,c) How many floating-point registers does the Athlon have? Are these
> all 80 bits? Are they accessed via the same kind of stack-based model as
> the Pentium?
> 

Apparently the Athlon has three floating point pipelines: 1 FMUL, 1 FADD,
and 1 store pipeline. These split 3DNow and MMX instructions between them
as well as the FPU ones; the only other FPU data we are given is that
there are 88 floating point registers in the register file.

No examples, no stall rules, no latencies, no store bypassing rules, no
decoding rules (for FP) nothing. AMD's K6 family optimization manual was
exactly the same. Lots of luck getting any performance tuning done at all.
It's not even clear that FPU instructions can issue in parallel with
integer instructions (I believe they can, but the two units share the same
three decoders).

I would love for someone to club me over the head and tell me where all
that info is located

jasonp

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------------------------------

Date: Wed, 9 Feb 2000 16:40:46 EST
From: [EMAIL PROTECTED]
Subject: Mersenne: Re: Mersenne Digest V1 #690

What I would love to see on the individual account report is the work rate of 
each machine......

eg. 
P90 hrs/day total and P90 hrs/day in the last month or so.

Is this possible????

Lawrence......


In a message dated 09/02/70, 10:26:53, [EMAIL PROTECTED] writes:
<<>Would it be possible to add a CPU type/speed column to the 
>"Exponents Assigned" list of the "Individual Account Report"?

I second that, and move that a program/version line also be added,
to both the individual account report and the cleared exponents list.>>
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------------------------------

Date: Wed, 9 Feb 2000 16:41:39 -0500
From: "Rick Pali" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: PrimeNet Top Producers List

From: Scott Kurowski

> Following the database synchro we performed on
> PrimeNet yesterday...

I noticed the addition of the machine speeds and software version to my
individual account report. Now that's what I call being responsive to user
requests!

Rick.
- -+---
[EMAIL PROTECTED]
http://www.alienshore.com/

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------------------------------

Date: Wed, 9 Feb 2000 23:19:34 +0100 
From: Jan Munch Pedersen <[EMAIL PROTECTED]>
Subject: RE: Mersenne: .. Amicable ..

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.

- ------_=_NextPart_001_01BF734B.BEDD0D04
Content-Type: text/plain

Sorry, a little of topic...

> The recent heroes in this field are H J J te Riele, who "knows
> everything about amicable numbers" according to a now forgotten usenet
> poster and Lee and Madachy, who published "The history and discovery of
> Amicable Numbers" in the Journal of Recreational Mathematics in 1972,
> 
Your list of heroes are far out of date. Here are some recent heroes:
- - Herman te Riele: still knowing (almost) everything about amicable pairs.
- - Stefan Battiato&Walter Borho: early mass production of pairs (30,000+),
first pair with members coprime to 6.
- - Holger Wiethaus: the first pair with over 1000 digits (and producing
10,000+
pairs).
- - Derek Ball: independent mass production and still very active.
- - Frank Zweers: many pairs with 1000+ digits.
- - Mariano Garcia: 80+ years old, still very active, holds record with
a 5577 digit pair found in 1997.
- - Yasutoshi Kohmoto: first pair with members coprime to 30.
- - David Moews&Paul Moews: all pairs < 3*10^11 using a sieve algorithm.
- - David Einstein: nearly all pairs < 10^13 using a tree algorithm.
- - Patrick Costello: methods for type (n,1) pairs and still very active.

> There are far more amicable pairs known than even perfect numbers, yet
> Guy's claim on their infinite number or otherwise is, surprisingly,
> weaker. "It is not known if there are infinitely many, but it is
> believed that there are."
> 
Please visit http://www.vejlehs.dk/staff/jmp/aliquot/knwnap.htm
for a list of 550,000+ amicable pairs. My database is growing with
around 50,000-100,000 pairs every year, so, yes without any doubt
there is an infinite number of amicable pairs.

Best wishes
Jan



- ------_=_NextPart_001_01BF734B.BEDD0D04
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Content-Transfer-Encoding: quoted-printable

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<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Dus-ascii">
<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
5.5.2448.0">
<TITLE>RE: Mersenne: .. Amicable ..</TITLE>
</HEAD>
<BODY>

<P><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">Sorry, a little of =
topic...</FONT>
</P>
<UL>
<P><FONT SIZE=3D2 FACE=3D"Arial">The recent heroes in this field are H =
J J te Riele, who &quot;knows</FONT>
<BR><FONT SIZE=3D2 FACE=3D"Arial">everything about amicable =
numbers&quot; according to a now forgotten usenet</FONT>
<BR><FONT SIZE=3D2 FACE=3D"Arial">poster and Lee and Madachy, who =
published &quot;The history and discovery of</FONT>
<BR><FONT SIZE=3D2 FACE=3D"Arial">Amicable Numbers&quot; in the Journal =
of Recreational Mathematics in 1972,</FONT>
</P>
</UL>
<P><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">Your list of heroes =
are far out of date. Here are some recent heroes:</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Herman te Riele: =
still knowing (almost) everything about amicable pairs.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Stefan =
Battiato&amp;Walter Borho: early mass production of pairs =
(30,000+),</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">first pair with =
members coprime to 6.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Holger Wiethaus: =
the first pair with over 1000 digits (and producing 10,000+</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">pairs).</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Derek Ball: =
independent mass production and still very active.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Frank Zweers: =
many pairs with 1000+ digits.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Mariano Garcia: =
80+ years old, still very active, holds record with</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">a 5577 digit pair =
found in 1997.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Yasutoshi =
Kohmoto: first pair with members coprime to 30.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- David =
Moews&amp;Paul Moews: all pairs &lt; 3*10^11 using a sieve =
algorithm.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- David Einstein: =
nearly all pairs &lt; 10^13 using a tree algorithm.</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">- Patrick Costello: =
methods for type (n,1) pairs and still very active.</FONT>
</P>
<UL>
<P><FONT SIZE=3D2 FACE=3D"Arial">There are far more amicable pairs =
known than even perfect numbers, yet</FONT>
<BR><FONT SIZE=3D2 FACE=3D"Arial">Guy's claim on their infinite number =
or otherwise is, surprisingly,</FONT>
<BR><FONT SIZE=3D2 FACE=3D"Arial">weaker. &quot;It is not known if =
there are infinitely many, but it is</FONT>
<BR><FONT SIZE=3D2 FACE=3D"Arial">believed that there are.&quot;</FONT>
</P>
</UL>
<P><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">Please visit <A =
HREF=3D"http://www.vejlehs.dk/staff/jmp/aliquot/knwnap.htm" =
TARGET=3D"_blank">http://www.vejlehs.dk/staff/jmp/aliquot/knwnap.htm</A>=
</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">for a list of =
550,000+ amicable pairs. My database is growing with</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">around =
50,000-100,000 pairs every year, so, yes without any doubt</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">there is an =
infinite number of amicable pairs.</FONT>
</P>

<P><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">Best wishes</FONT>
<BR><FONT COLOR=3D"#0000FF" SIZE=3D2 FACE=3D"Arial">Jan</FONT>
</P>
<BR>

</BODY>
</HTML>
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------------------------------

Date: Wed, 9 Feb 2000 22:35:07 -0000
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Re: optimizing for Athlon

On 9 Feb 00, at 15:36, [EMAIL PROTECTED] wrote:

> >The optimization that should probably be done for Athlon is to 
> >organize the code to allow FMUL & FADD to execute in parallel (which the
> >Pentium II/III core just can't manage). This could give a speedup of the
> >order of 40%.
> 
> That would be nice if true, but I suspect it's a bit overoptimistic.
> The reason is this: the Athlon utilizes out-of-order execution, i.e.

Yes, that's why I wrote "could", as opposed to "should". How much 
benefit you get from OOE depends to an enormous extent on how the 
code is organized. If you've just retired registers containing 
temporary results which you need back to work on _right now_ then you 
could be working rather inefficiently.

You've made the point in the past that organizing HLL source code 
"properly" gives the optimizer in the compiler a better chance of 
doing a decent job; the same is no less true in that well-organized 
assembler code gives the execution scheduler in the CPU less of a 
chance to foul things up.
> 
> 1a,b,c) How many floating-point registers does the Athlon have? Are these
> all 80 bits? Are they accessed via the same kind of stack-based model as
> the Pentium?

>From the briefing notes I have (which are quite elderly and may not 
correspond with the consumer silicon);
so far as x86 compatible FP operations are concerned,
a) there are 40 FPU registers but only 8 of them are named. (The 
others are available to hold temporaries etc). This register pool is 
shared with the 3D-Now instruction set.
b) Yes. (In 3D-Now mode they actually contain 128 bits)
c) The 8 named FP registers are logically organized as a stack just 
like the Intel model. (Unchanged since the 8087!)

> 2a,b,c) I believe the Athlon has two floating adders in addition to a
> floating multiplier. Can it dispatch 2 FADDs and 1 FMUL per cycle? Can it
> do 2 double- precision FADDs per cycle, or just do single-precision adds
> in parallel?

a) There are two independent 80-bit FP execution units, both can do 
FADD but only one can do FMUL.
b) No. You can do 2 FADDs or 1 FADD + 1 FMUL per cycle.
c) I think in 3D-Now mode you can do 4 SP operations in parallel in 
each execution unit instead of one 80-bit operation.


Regards
Brian Beesley
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------------------------------

Date: Wed, 09 Feb 2000 16:32:29 -0800
From: Mike Bandsmer <[EMAIL PROTECTED]>
Subject: Re: Mersenne: pi

At 02:31 AM 2/9/00 -0500, gav wrote:
>  I think my favorite counterexample to arguments like this is Gabriel's
>Horn.  Take the function 1/x, and revolve it around the x-axis.  You now
>have something that looks very similar to a trumpet's bell.  Now, find the
>volume of this from 0 to infinity.  It has a finite volume.  However, it
>has an infinite surface area.  

I have a little trouble conceptualizing what would happen if you fill this
horn with paint.  If you completely fill this horn with paint (a finite
volume), the inner surface of the horn should be completely covered with
paint, right?  But the inner surface of the horn has infinite area, so
wouldn't it take an infinite amount of paint to paint it?  Where is my
intuition going wrong?

Mike


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Date: Wed, 9 Feb 2000 20:35:20 -0500
From: "Ethan O'Connor" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: pi

>-----Original Message-----
>From: [EMAIL PROTECTED]
>[mailto:[EMAIL PROTECTED]]On Behalf Of Mike
>Bandsmer
>Sent: Wednesday, February 09, 2000 7:32 PM
>To: [EMAIL PROTECTED]
>Subject: Re: Mersenne: pi
>
>
>At 02:31 AM 2/9/00 -0500, gav wrote:
>>  I think my favorite counterexample to arguments like this is Gabriel's
>>Horn.  Take the function 1/x, and revolve it around the x-axis.  You now
>>have something that looks very similar to a trumpet's bell.  Now, find the
>>volume of this from 0 to infinity.  It has a finite volume.  However, it
>>has an infinite surface area.
>
>I have a little trouble conceptualizing what would happen if you fill this
>horn with paint.  If you completely fill this horn with paint (a finite
>volume), the inner surface of the horn should be completely covered with
>paint, right?  But the inner surface of the horn has infinite area, so
>wouldn't it take an infinite amount of paint to paint it?  Where is my
>intuition going wrong?

It would take infinite area of an infinitesimally thin layer of paint, which
would have no volume due to its thinness. Since paint can't be infinitely
thin,
this also means you can't actually fill the object with paint, because there
will be volume in areas into which paint molecules can't fit.

Mike

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Date: Thu, 10 Feb 2000 09:58:28 +0800
From: "Low Hwee Boon"<[EMAIL PROTECTED]>
Subject: Mersenne: PI is a transcendental number

 I recall my study of Maths in high school:-

 1. First we learn about Integers : 0, 1, 2, 3,.. positive and negative
 2. Then about Decimals : 0.1, 0.23, 3.5 etc
 3. Follow by Fractions in the form of a/b where a and b are integers.
 4. By converting fractions to decimals, we discover infinite but
repetitive sequence
     e.g. 2/9 = 0.2222....; 17/27 = 0.629629629...with infinite repetition
of 629
 5. And the study of geometry and algebra introduce Irrational numbers.
     e.g. square root of 2 = 1.414213562373.... to infinity small without
any repetitive sequence.
    Basically, an irrational number is one that cannot be expressed by a
fraction of integers.
    And any numbers that can be expressed by a fraction is called rational
number.
 6. But most irrational numbers can be obtained from solving a polynomial
equations
     e.g. x**2-2 = 0 gives rise to x = +/- sqrt root 2.
 7. And we learn about Imaginary number from solving equation such as
     X** 2 + 4 = 0 gives rise to x = +/- 2i
 8. Finally, Pi and "e" were introduced as Transcendental numbers :-
     Those irrational numbers that cannot be derived from the roots of any
Polynomial Equations!

 Integers, Decimals, Fractions, Irrational, and even Transcendental
Numbers, they
 are all FINITE and PRECISE (can be precisely defined). Such properties
hold irregard
 what sort of Numeric Representation (such as Binary, Hexadecimal etc).

 9. Euler had marvellously combined all the above into one equation
     "e" to the power of i (imaginary) * PI = -1.

 Thanks to my Maths teachers for showing the wonders of the Numbering
System
 HweeBoon



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------------------------------

Date: Wed, 09 Feb 2000 21:05:41 -0500
From: gav <[EMAIL PROTECTED]>
Subject: Re: Mersenne: pi

  You're on the right track, but the mistake you're making is that the
paint can be infinitesimally thin in order to coat the surface.  So, if the
thickness of the paint decreases proportionately to the function, then
you've only used a finite amount of paint (as the volume is only finite),
but you've coated an infinite surface area.
  If someone happens to remember the exact way the integral are written,
that'd be a big help.  I'm going to try and find my old Calc text now, I'm
sure it's in there somewhere.

gav

At 04:32 PM 2/9/00 -0800, Mike Bandsmer wrote:
>At 02:31 AM 2/9/00 -0500, gav wrote:
>>  I think my favorite counterexample to arguments like this is Gabriel's
>>Horn.  Take the function 1/x, and revolve it around the x-axis.  You now
>>have something that looks very similar to a trumpet's bell.  Now, find the
>>volume of this from 0 to infinity.  It has a finite volume.  However, it
>>has an infinite surface area.  
>
>I have a little trouble conceptualizing what would happen if you fill this
>horn with paint.  If you completely fill this horn with paint (a finite
>volume), the inner surface of the horn should be completely covered with
>paint, right?  But the inner surface of the horn has infinite area, so
>wouldn't it take an infinite amount of paint to paint it?  Where is my
>intuition going wrong?
>
>Mike
>
>
>_________________________________________________________________
>Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
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>
>

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------------------------------

Date: Wed, 9 Feb 2000 18:27:53 -0800
From: "John R Pierce" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: pi

From: "Ethan O'Connor" <[EMAIL PROTECTED]>
To: "'Mike Bandsmer'" <[EMAIL PROTECTED]>,
        "Mersenne List \(E-mail\)" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: pi
Date: Wed, 9 Feb 2000 20:35:20 -0500
Message-ID: <001301bf7367$1842f410$1a88da18@HIGHLAND>
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

could you perhaps disable this?  its rather annoying to be asked
repeatedly if I want to auto-acknowlege your email, and I'm sure
you really didn't intend for every subscriber to this list
to acknowlege receipt of your every posting.

- -jrp


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------------------------------

Date: Wed, 09 Feb 2000 21:29:16 -0500
From: Jud McCranie <[EMAIL PROTECTED]>
Subject: Re: Mersenne: PI is a transcendental number

At 09:58 AM 2/10/00 +0800, Low Hwee Boon wrote:
 > 6. But most irrational numbers can be obtained from solving a polynomial
>equations


Actually almost all irrational numbers are transcendental, and therefore 
not the root of a polynomial with rational coefficients.


+--------------------------------------------------------+
|                  Jud McCranie                          |
|                                                        |
| 137*2^197783+1 is prime!  (59,541 digits, 11/11/99)    |
| 137*2^224879+1 is prime!  (67,687 digits, 1/00)        |
+--------------------------------------------------------+

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------------------------------

Date: Wed, 9 Feb 2000 22:29:33 -0500
From: "Chris Nash" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: pi, limits, and other things OT

Hi folks

> >>  I think my favorite counterexample to arguments like this is Gabriel's
> >>Horn.  Take the function 1/x, and revolve it around the x-axis.  You now
> >>have something that looks very similar to a trumpet's bell.  Now, find
the
> >>volume of this from 0 to infinity.  It has a finite volume.  However, it
> >>has an infinite surface area.
>   If someone happens to remember the exact way the integral are written,
> that'd be a big help.  I'm going to try and find my old Calc text now, I'm
> sure it's in there somewhere.

If y=f(x), the volume of revolution is given by

{integral from 1 to infinity) pi.y^2 dx

Note the integral starts at 1, not zero (otherwise the volume is undefined)
for the Horn. The volume is in fact pi.

The surface of revolution is given by

(integral from 1 to infinity) 2.pi.y.sqrt(1+y'^2) dx

where y'=dy/dx= -1/x^2 in the case of the horn.

The integrand is 2.pi.x /sqrt(x^4+1). If you recognise this, good for you
(Apply a change of variable t=x^2 and you will get pi. 1/sqrt(t^2+1) under
the integral, which you might recognize. If you're still stuck, think about
arcsinh t).

Recognize it or not, it really doesn't matter, Note the integrand is
actually a little greater than

2 pi y dx

which is the usual mistake first made with surfaces of revolution
(approximating the surface by 'delta-x height cylinders' instead of 'delta-x
height slices of cones'). However this function is a lot easier to recognize
as the derivative of 2.pi.ln x, and so the integral as we approach infinity
is indeed unbounded.

> >I have a little trouble conceptualizing what would happen if you fill
this
> >horn with paint.  If you completely fill this horn with paint (a finite
> >volume), the inner surface of the horn should be completely covered with
> >paint, right?  But the inner surface of the horn has infinite area, so
> >wouldn't it take an infinite amount of paint to paint it?  Where is my
> >intuition going wrong?

It's a bit like the old gag "how many lawyers does it take to wallpaper a
room?" ("Depends how thinly you slice them"). A given amount of paint or
lawyers can cover an arbitrarily large surface provided you spread it thinly
enough. Not possible in the real world of course (not to mention the Horn's
neck is ultimately too narrow to squeeze a paint molecule down), but
mathematicians aren't limited by such physical constraints.

Single-celled organisms have known for eons that the best way to improve
their rate of nutrition is to stretch their volume into the largest possible
surface area. Fortunately physics intervenes and an infinitesimally thin
organism of infinite length but finite volume isn't a biological
possibility.

Chris Nash
Lexington KY
UNITED STATES


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------------------------------

Date: Wed, 9 Feb 2000 23:44:58 EST
From: [EMAIL PROTECTED]
Subject: Mersenne: Re: Mersenne Digest V1 #690

<<It has a finite volume.  However, it has an infinite surface area. >>

One of my friends, AYL (who proofread my Mersennes paper) loves to talk about 
Gabriel's Horn. His favorite comment is: "So, I can pour paint INTO the 
thing, but I can't paint it?"

Stephan Lavavej
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Date: Thu, 10 Feb 2000 01:10:23 -0600
From: Ken Kriesel <[EMAIL PROTECTED]>
Subject: RE: Mersenne: pi

At 08:35 PM 2/9/2000 -0500, <[EMAIL PROTECTED]> wrote:
>It would take infinite area of an infinitesimally thin layer of paint, which
>would have no volume due to its thinness. Since paint can't be infinitely
>thin,
>this also means you can't actually fill the object with paint, because there
>will be volume in areas into which paint molecules can't fit.
>
>Mike

Filling the horn with paint has a couple additional problems:

since it is an infinitely long capillary, filling time would be infinity^4
or so (laminar flow conductance being proportional to diameter^4
and inversely proportional to length)

A realizable section of Gabriel's horn would necessarily be lumpy
when constructed of real material.  Think of a tube constructed
of soccer balls glued together.  If the horn inner diameter is a kilometer,
great, it looks pretty smooth.  (Say for the sake of argument the
diameter of these soccer balls is 3 decimeters.)
But further along, where the inner
diameter has fallen off to one meter, it's beginning to look pretty
lumpy already, and when inner diameter drops to 1 decimeter,
the tube roughness is very significant.
Now move out to where the inner diameter is 1 Angstrom,
and the atoms of which the wall is constructed are 3 Angstroms
diameter, and it looks the same.

I'm surprised noone responded about continued fractions to
Ian Halliday:
At 10:42 PM 2/9/2000 +1300, [EMAIL PROTECTED] wrote:
>Over history, there have been numerous other approximations to the value
>of pi. Our current culture seems to favour 22/7 as an approximation, and
>the Biblical approximation above suggests 333/106. However, this is not
>the best available in three digits, which is, so far as I know, 355/113,
>which is correct to an astonishing one part in ten million. I understand
>that in certain quarters, 3 1/7 was not in vogue, with 3 1/8 favoured.
>What, argued these particular mystics, could be a better number than
>five squared shared by two cubed? N P Smith asked whether we should be
>more concerned by those who serious propose answers which are clearly
>wrong or by those who spend time in repeatedly refuting these spurious
>claims.

PI~=3.1415926535897932384626433832795
subtract the integer part, take the reciprocal of the rest, and iterate, to 
produce the continued fraction's coefficients.  
Reassemble successively increasing numbers of terms,
until the rational number obtained is sufficiently accurate.
This is an effective method of determining gear ratios approximating
arbitrary reals.

3+ 1 / (7 +
1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/(2+1/(1+1/(3+1/(1+1/(14+1/(2+1/(1+...))))
))))))) 
3= 3
4= 3 +1
3.14 2857142857... =3+1/7 = 22/7
3.1 25  = 3+1/(7+1) = 25/8
3.1415 09433962264150943396226415... =3+1/(7+1/15) = 3 + 15/106 = 333/106
3+1/(7+1/(15+1/)) =355/113, see below
3.141592 9203539823008849557522124... =3+1/(7+1/(15+1/1)) = 3 + 1/(7+1/16)=
3+1/(113/16) = 3+ 16/113 = 355/113
3+1/(7+1/(15+1/(1+1)))= 3.1415 525114155251141552511415525
3+1/(7+1/(15+1/(1+1/292))) = 103993/33102 = 3.141592653 0119026040722614947737
3+1/(7+1/(15+1/(1+1/293)))= 3.141592653 9214210447087159415927
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/1))))) = 3.141592653 4674367055204547853492
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1)))))) = 3.141592653
6189366233975003014106
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1))))))) = 3.1415926535
583573009183052053374
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/2))))))) = 3.14159265358
10777712044193065819
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/(2+1)))))))) = 3.1415926535
914039784825424142193
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/(2+1/(1+1)))))))))= 3.14159265358
70561991705458087813
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/(2+1/(1+1/3)))))))))=3.14159265358
9 3891715436873217069
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/(2+1/(1+1/(3+1))))))))))=3.1415926
53589 8153832419437773074
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/(2+1/(1+1/(3+1/2))))))))))=3.14159
2653589 6274836288508219852
3+1/(7+1/(15+1/(1+1/(292+1/(1+1/(1+1/(1+1/(2+1/(1+1/(3+1/(1+1/14)))))))))))=
80143857/25510582=3.14159265358979 26593756269457122


Ken

Ken Kriesel, PE <[EMAIL PROTECTED]>
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End of Mersenne Digest V1 #691
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