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In article <56odil$f4u@mark.ucdavis.edu>,
   psalzman@landau.ucdavis.edu (I hate grading almost as much as taking in 
class exams) wrote:
>hello
>
>i was wondering last night why it is that i've never seen fourier
>transforms used to solve ODE's.  i've used/seen fourier (and laplace)
>transforms for PDE's, but never a fourier tranform for an ODE.
>
>i tried the simplest toy problem i could come up.
>
>       f'(x) = 0
>
>which has the obvious solution of f(x) = constant.  transforming both
>sides of the equation to k space, we get:
>
>        ik F(k) = 0
>
>and tranforming back, we get:
>
>         f(x) = 0
>
>which is certainly a solution, but just not a very interesting one.  what
>is it about fourier transforms that makes them useful for PDE's but not
>ODE's?
>
>peter
the general solution to f'(x)=0 is f(x)=Const. if you FT f(x)=C you get 
F(k)=2*Pi*DiracDelta(k), since the integral involved doesn't converge in the 
usual sense.
anyway, the integral Int[f(x)*Exp[ikx],{x,-Inf,Inf}] must be defined in some 
sense, so f(x) should vanish at +-Infinity, which is a feature of the 
solutions of many physical problems, but of not so many solutions of arbitrary 
ODE's, i think. anyway, that's a bit heuristic, since i'm only a 
physics-student.
greetings
godzilla

On the Spinozan Method of Science
The Spinozan scientist is not common today or in any era.
-She learns to suspect authoritative declarations as improperly motivated and
 deceptive.
-She refuses academic degrees, chairs, and grants to preserve intellectual
 freedom.
-She scorns division of knowledge into academic disciplines.
-She studies peer review and the literature mainly as a source of illuminating
 errors, logical gaps, and silences.  Only specific allegations of illogic
 or of clashes with experience impell her to reexamine her work.
-She is ruthless self-effacing and methodical in her work to avoid all-too-
 human ulterior motives.
-She shows no mercy to any concept other than logical coherence, faithfulness
 to experience, or a contribution to ethics.  Even her native language may be
 sacrificed in favor of Latin or mathematics.
-She is diligent in criticism until she finds some principle capable of
 withstanding the most withering tests.  Then she is equally diligent in
 pursuing the consequences - especially ethical implications.
-She may publish posthumously to avoid physical retaliation for her discoveries.
-- 
Michael J. Burns                            http://www.indirect.com/www/mburns/
  "We are such stuff                             "Oh brave new world, 
   As dreams are made on, and our little life     That has such people in't!"
   Is rounded with a sleep."

  There once was this guy named MeGong
  Who claimed that Newton was wrong
  And not once in a while
  - or with a faint smile -
  he'd admit that his wording was strong.
The most dangerous untruths are truths slightly deformed.
Lichtenberg, Sudelbuecher
__________________________________
Lorenz Borsche
Per the FCA: this eMail adress is not to 
be added to any commercial mailing list.
Uncalled for eMail maybe treated as public.

The unceratinty principle is essentially a statement that
the 'act of measurement' cannot be described by a differential equation
(which essentially embodies causality in time).
Only probabilities can be computed regarding the outcome of 'measurements'.
Since probabilities is all that you have, there will always be uncertainties
associated with 'measurements'.
-- 
Tony Richards            'I think, therefore I am confused'
Rutherford Appleton Lab  '
UK                       '

brian artese wrote:
> 
> Hardy Hulley wrote:
> 
> >> Brian has already addressed your cites, so I won't bother...
> >
> > Your standards are too modest.
> 
> Uh huh... I notice you didn't have an answer for my post...
> IMHO, it pretty clearly revealed you have no idea what deconstruction
> is about -- you know, the thing you're arguing against.
Perhaps you'll send the post you refer to (or a summarised version)
again. I can't find it.
> > Deconstructionism may well consist of texts. Philosophy, in
> > contradistinction, comprises concepts, ideas, analysis, rational
> > argument, and the search for truth - in other words, hard work. Texts
> > are merely peripheral to this enterprise - they provide the 
> > mechanisms whereby the essence of philosophy may be stored,
> > cross-referenced, and passed on from generation to generation.
> 
> I'm not trying to be insulting here, but, really this is too funny.  Do
> you seriously believe that philosophy is an activity that takes
> place--where?--in the air somewhere?
No, in the minds of philosophers.
> That the actual *articulation* of
> philosophy--its existence as written or spoken words--is, what, just
> some epiphenomenal product?  Could you possibly give an example of a
> philosopher whose work is *not* the outgrowth of the things he or she
> has read, or heard spoken?
Kurt Godel.
Cheers,
Hardy

Michael Warner wrote:
> IMHO: "What kind'a bait you usin'?". IYKWIM, AITYD.
Let's see:
I know IMHO, but I've never seen the others.
IYKWIM: If you know what I mean?
AITYD:	And I trust you do?
Reminds me of Goedel.
Roger Leemann

In article: <56i8ph$4lp@dfw-ixnews11.ix.netcom.com>
  odessey2@ix.netcom.com(Allen Meisner) writes:
> 
>     Each buoy has its own observer. The observer in buoy 1 shines the
> laser in his own buoy. He himself determines whether he is at absolute
> rest by observing whether the laser beam that he shines is deflected.
> The same goes for buoy two. If both are at absolute rest, by defintion
> they can not be moving at any velocity whatsoever.
> 
> Regards,
> Edward Meisner
In the real world however, the beams aren't "deflected" regardless of the 
velocity of the source.
-- 
George Dishman
Give me a small laser and I'll move the sun.

Hi, this might seem to be dumb to you, but I need to know how to build
an accelerometer (aside from cork tied with a string to the bottom of
a water filled container)
Can anyone help me out??? 

In article: <56e8ch$ffl@Starbase.NeoSoft.COM>
  positron@Starbase.NeoSoft.COM (Jonathan Haas) writes:
> 
> Vladimir A. Pertsel  wrote:
> >"Dmitri V. Papichev"  wrote in relcom.rec.puzzles:
> >(Translation only)
> >[...]
> >49 absolutely identical insulated wires cross the river under the 
> >water. The ends of each wire are on the opposite banks of the river, 
> >disconnected  initially. There is an electricity source on one of 
> >the banks. An electrician with a tester (*) has to label all the 
> >wires (0 - 48) (Each wire should have the same label on its both ends).
> >A boatman charges 1 rouble for each crossing of the river.
> >What is the minimal sum of money, sufficient for the electrician to 
> >fulfill the task?
> >
> >(*) The tester allows to determine whether the wire is
> >    connected to the electricity source, when You touch 
> >    the wire by the tester.
> 
> Seen it. Good one, though. Spoiler below...
> 
> 
> 
> He can do it in two crossings of the river.
> 
An engineer's answer - One crossing:  label all the wires and put the ends in 
the river well separated.  Cross the river.  Connect one terminal of the power 
source to a heavy uninsulated wire and throw it in the river.  Connect each 
wire in turn to the other terminal and note from which wire the bubbles rise 
on the other side.
;)
-- 
George Dishman
Give me a small laser and I'll move the sun.

A few years ago, one second was added to all the clocks
of the world. I think it was done because the earth's
rotating speed is decreasing. But, according to W. Greiner
(German scientist), the day is today only 0.0165 seconds
longer than 1000 years ago, which means that one second
should only be added each 166 years.
Therefore, I'd like to ask a few questions:
1) am I wrong?
2) if not, is Greiner wrong?
3) if not, why didn't we wait a little century before
   changing the time?
Thanks
---
Olivier Glassey
Inst. math.
University of Fribourg
Switzerland

"Lionel PORCHERON"  wrote:
>Does somebody know how Pi was discovereed by the greek and how did they
>found the relation between the perimeter of the circle, the surface of the
>disk and the ray? 
>I would like to know to, how we calculate now the value of Pi (we can say
>with Maple for Instance that Pi is:
>3.14159265358979323846264338327950288419716939937510582097494459230781640628
>6208998628034825342117068)
>
"A History of Pi" Petr Beckmann, which also has pi to 10,000 decimal 
places.
Pi is all over the Net ( http://www.search.com/ ) including multilanguage 
poems at a Caltech server.  If you want pi to 500,000 places, drop me an 
e-mail for the PKZIP compression.
-- 
Alan "Uncle Al" Schwartz
UncleAl0@ix.netcom.com ("zero" before @)
http://www.ultra.net.au/~wisby/uncleal.htm
 (Toxic URL! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?"  The Net!

Steve Marotta  wrote:
>Hi there, I'm a lowly high school student with a homework problem that's
>probably very very simple for any of you people, but I'm just not seeing
>it.  Okay, here we go.  This is the problem, exactly as it appars:
>
>Two blocks of masses M and m approach each other on a horizontal table
>with the same constant speed, vo, as measured by a laboratory observer. 
>The blocks undergo a perfectly elastic collision, and it is observed
>that M stops while m moves opposite its original motion with some
>constant speed, v.  (A) Determine the ratio of the two masses, M/m.  (B)
>What is the ratio of their speeds, v/vo?
>
>This is a quick problem, but it's bugging the bejeesus out of me. 
>Please, if any of you have just a couple of minutes, I'd really
>appreciate some help on this :)  Thanks.
Momentum is conserved, energy is conserved.  You can analyze the motion 
from any of the three frames of reference.
That M is stopped lets everything else fall into place.
-- 
Alan "Uncle Al" Schwartz
UncleAl0@ix.netcom.com ("zero" before @)
http://www.ultra.net.au/~wisby/uncleal.htm
 (Toxic URL! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?"  The Net!