HDTenEightyP/NetNews huggingface dataset:
From: frederic@vivaldi.cs.unc.edu (Robin Fredericksen)
Newsgroups: sci.math.symbolic
Subject: Re: Using Mathematica to fit a surface to data(+ another Q?)
Keywords: Mathematica, curve fit, surface plot
Date: 19 Dec 92 18:15:51 GMT
Organization: The University of North Carolina at Chapel Hill

In article <1gst2gINNfsk@tamsun.tamu.edu> bryan@kolsky.tamu.edu (Bryan Milligan) writes:
>
>	Is there a routine in Mathematica to fit a surface to a set of
>(x,y,z) data?  I have some FEM data that I need to differenciate, and I
>would like to fit a polynomial curve to the data and differenciate that
>as opposed to numerically differenciating the data itself.
>
>--
>
>Bryan Milligan
>Department of Aerospace Engineering
>Texas A&M University
>bryan@kolsky.tamu.edu  (NeXT Mail accepted)


I use the Interpolate function to do this.  The data points have 
to be on a grid in that the sample set must be complete on the
axis but the sample grid can be irregular.  There can be any
(unlimited?) number of dimensions to the data, and you can
(with the caveat that I describe below in my own question)
specify the order of the polynomial used for interpolation.
I don't know whether you can use other functions (e.g. sinusoids,
etc.)

Now, my problem is somewhat different, and has to do with the 
Interpoate[] function, so I will ask the NET since it is directly 
relevant to you if you would like to use it. :-)

====NEW BUT RELATED QUESTION====
I am using Mathematica (on a Mac) for reading in a data file
with points with a non-square (non-regularly spaced) grid of points.

(i.e. sample points that look like)

	0	0		0				0
	0	0		0				0

	0	0		0				0



	0	0		0				0





	0	0		0				0



I am using the Interpolate[] function that mathematica offers

	Function = Interpolate[ <datalist>, InterpolationOrder->1]


As I understand the manual, this should create a function which 
provides as output the above data with linear interpolation between 
the points.  However the output that I get from this is definately 
NOT a linear interpolation, but something that looks quadratic.

Can anyone tell me how to fix this?  Is there a simple work-around?

Please email responses to frederic@cs.unc.edu
as well posting, if possible.

Thanks.
Eric Fredericksen
frederic@cs.unc.edu
-- 
-------------------------------------------------------------------------------
Eric Fredericksen	: Insert amazingly funny or enlightening quote
frederic@cs.unc.edu	: in this space here.
I don't need a disclaimer, I'm a graduate student so no one cares what I say...
Newsgroups: sci.math.symbolic
From: limber@euclid.Colorado.EDU (Mark Limber)
Subject: Student Version of MapleV Release 2??
Originator: limber@euclid.Colorado.EDU
Organization: University of Colorado, Boulder
Distribution: na
Date: Sat, 12 Dec 1992 19:25:37 GMT

The title says it all.  Is there a student version 
of MapleV Release 2?


mark
Newsgroups: sci.math.symbolic
From: eboltz@jhunix.hcf.jhu.edu (Eric Scott Boltz)
Subject: Two Question re: Mathematica
Organization: HAC - Johns Hopkins University, Baltimore
Date: Thu, 17 Dec 1992 23:04:51 GMT

Two questions:

1) anybody know how to run Mathematica with different terminal
graphics? The program resides on a NeXT, but I'd like to do some
plotting when I'm at a remote location (i.e. no NeXT).

2) what's the address for the Mathematica email group? I think
it's something like mathgroup@yoda.something.etc.

Thanks,
Eric S. Boltz
NIST Boulder
JHU
From: c9e-aw@volga (Claudio Fahey)
Newsgroups: sci.math.symbolic
Subject: Phone number for WRI?
Date: 12 Dec 92 00:04:34 GMT
Organization: University of California, at Berkeley

Does anybody have the phone number for Wolfram Reasearch?  I looked all over
some periodicals and books about Mathematica but I couldn't find it.  Thanks.
Newsgroups: sci.math.symbolic
From: steve@physics.unc.edu (Steve Christensen)
Subject: Re: How can I get Mma. to do this ??
Organization: MathSolutions, Inc. - Chapel Hill, NC
Date: Fri, 11 Dec 1992 21:44:30 GMT

Yet another comment about MathTensor since it has been mentioned.
The goal of MathTensor is not just to help with relativity computations.
In fact, we have users in physics, math, engineering, computer graphics, 
chemistry and even medical research.  Over time we expect to directly
support all of these areas with special MathTensor packages.  We
are actively learning the needs of all of these areas.  Since we 
obviously cannot be experts in research areas as diverse as the
ones above, we also provide as much programmibility and flexibility
into our functions and objects as we can so that we can help users do what
they need.  We are anxious to hearrom people with an interest
in tensors to get ideas for future developments.  In fact, we have
and continue to communicate with the developers of systems written
in other CA languages or for different audiences.  Tensors are
becoming more and more important in many research areas and there
is room for many programs - both commercial and PD.

I would be happy to investigate any suggested problems readers
might like to submit.

Steve Christensen




Newsgroups: sci.math
From: solan@smaug.uio.no (Svein Olav G. Nyberg)
Subject: Re: 3D motion solution of Rubic's Cube?
Followup-To: sci.math
Keywords: Rubic's Cube, Graphics
Reply-To: solan@smaug.uio.no (Svein Olav G. Nyberg)
Organization: University of Oslo, Norway
Date: Fri, 18 Dec 1992 19:08:53 GMT

In article <1992Dec18.160151.7916@cbfsb.cb.att.com>, pgm@jolt.att.com
(Patrick G. Maggiulli) writes:
|> Can someone share with me, and others, your comments,
|> advice and/or experiences about this topic?

Why not solve the cube yourself. Its really easy.
If you have no recipe, I can tell you the one I made
up in those crazy days.

Solan (solan@math.uio.no)
Newsgroups: sci.math
From: psm@burra.ee.mu.OZ.AU (Phil Malin)
Subject: Tensor derivatives
Organization: Electrical and Electronic - University of Melbourne 
Date: Thu, 17 Dec 1992 04:31:41 GMT

Hi all.

This question may not make sense, but anyway...

I've read about covariant and contravariant derivatives.  Does it
make sense to have mixed tensor derivatives?  i.e. taking the derivative
of a function w.r.t. a type (1,1) tensor, etc... if the function is
a function of this tensor?  Does this question make sense?

If it does exist could someone supply me with some references, the
books I have on the subject don't go into this sort of thing.

If, on the other hand, this idea shows a total lack of understanding
of the subject please inform me gently (no flames :-).

Thanks.

Phil Malin.
psm@mullian.ee.mu.oz.au
From: fred@cybernet.cse.fau.edu (Fred Richman)
Newsgroups: sci.math
Subject: Gravitational waves
Date: 19 Dec 92 18:47:44 GMT
Organization: Cybernet BBS, Boca Raton, Florida

I have some information that Lars Samuelson requested on
gravitational waves, but no e-mail address that works.
From: koc@rize.ECE.ORST.EDU (Cetin Kaya Koc)
Newsgroups: sci.math
Subject: Re: What is the number
Date: 17 Dec 92 19:48:16 GMT
Article-I.D.: flop.1gqli0INN3i6
Organization: College of Engineering, Oregon State University
NNTP-Posting-Host: rize.ece.orst.edu

>    Whose sum of the factorials of the digits is the number itself

Also 40585 = 4! + 0! + 5! + 8! + 5! = 24 + 1 + 120 + 40320 + 120
                                    = 40585
From: cxm7@po.CWRU.Edu (Colin Mclarty)
Newsgroups: sci.math
Subject: Re: Ref. for existence of universal objects?
Date: 17 Dec 1992 19:24:49 GMT
Organization: Case Western Reserve University, Cleveland, OH (USA)
Reply-To: cxm7@po.CWRU.Edu (Colin Mclarty)
NNTP-Posting-Host: slc5.ins.cwru.edu


In a previous article, frandag@math.ksu.edu (Francis Fung) says:

>
>I was just wondering if anyone knew of a comprehensible reference
>for a proof that there exist universal objects in categories satisfying
>certain conditions, which I don't really understand. The reference
>in Massey's Alg. Top.: An Intro. was to Bourbaki's Theory of Sets, 
>but the terminology is essentially impenetrable for me. Perhaps there
>is a more modern treatment somewhere. Any input is welcomed!
>Francis Fung
>
	Probably the clearest is Mac Lane's _Categories for the Working
Mathematician_ p.124.  He puts it as existence of an initial object, but
a universal object is a kind of initial object (initial in a comma
category, as Mac Lane remarks on p.56).

	Bourbaki's notion is not category theoretic but an in-house 
creation after internal debates on category theory.  It never caught 
on even in Bourbaki's mathematical practice.  This affair is described
by Leo Corry in "Nicholas Bourbaki and the concept of mathematical
structure"  in _Synthese_92_: 315-348 (1992).

Colin McLarty
Newsgroups: sci.math
From: sbardhan@uncc.edu (Soumendu Bardhan)
Subject: What is the number
Reply-To: sbardhan@uncc.edu
Organization: University of NC at Charlotte
Date: Thu, 17 Dec 1992 05:06:44 GMT

Whose sum of the factorials of the digits is the number itself
( no programming please !).


Newsgroups: sci.math.stat
From: thompson@atlas.socsci.umn.edu (T. Scott Thompson)
Newsgroups: sci.math.stat
Subject: WANTED:  Phone number for SPSS Inc.
Date: 17 Dec 92 16:23:22 GMT
Reply-To: thompson@atlas.socsci.umn.edu
Organization: Economics Department, University of Minnesota

I tried calling the (800) 543-5381 number for SPSS Inc. in the latest
AmStat News.  I got a recorded message that the number "is not
available from my calling area."  Furthermore, 800-information has
never heard of SPSS Inc.

Does anyone have another direct dial phone number for them please?

E-mail replies preferred since I am in a bit of a rush.

Thanks in advance.

P.S.  Any opinions on the pros / cons of SPSS/PC+ are also welcome.
--
T. Scott Thompson              email:  thompson@atlas.socsci.umn.edu
Department of Economics        phone:  (612) 625-0119
University of Minnesota        fax:    (612) 624-0209
From: gyan@unixg.ubc.ca (Gyan P. Sinha)
Newsgroups: sci.math.stat
Subject: Estimation of spline join points? References, suggestions?
Date: 15 Dec 92 21:42:39 GMT
Organization: The University of British Columbia
NNTP-Posting-Host: unixg.ubc.ca
Summary: Estimating Spline join points
Keywords: Splines, join points, Maximum-Likelihood

Hello all:

	I am estimating the parameters of a censored regression model
(panel tobit), and one of the variables has a non-linear effect on
the dependent variable. I am trying to use a spline to model this, 
and its defined as:

	V1 = THETA + MIN(DIFF-THETA,0)
	V2 = MAX(DIFF-THETA,0)

so that if DIFF is less than THETA, then the effect on the dependent
variable is different than when it is larger, and V1 and V2 are the
two secondary independent variables created from the DIFF variable.
Instead  of imposing a value on THETA, I'd like to be able to estimate
it from the data itself. 

My questions are:

(1) OPTIMIZATION STRATEGY: ML estimation will require some type of
non-gradient  technique (?), so how do I get the asymtotic t-stats and
such? 

(2) MEANING OF T-STATS: If I am estimating the join point from the
data itself, does that require some special tweaking on the t-ratios
to get legitimate tests of significance?


(3) REFERENCES: Can anyone suggest references that I can explore on
this problem?

(4) ALTERNATIVES: Can anyone suggest alternatives that would allow for
similar effects, other than introducing a polynomial in DIFF, of which
I'm already aware of.

Thanks for any assistance.


Seasons Greetings!

Gyan P. Sinha
UBC, Vancouver.
From: feh@duke.edu (Frank Harrell)
Newsgroups: sci.math.stat
Subject: stepwise regression
Date: 17 Dec 92 15:42:03 GMT

Backward elimination does not at all dominate full model fitting.
See:

@article{hou90pre,
   author = {{Van Houwelingen}, J.C. and {Le Cessie}, S.},
   journal = "Statistics in Medicine",
   pages = {1303-1325},
   title = {Predictive value of statistical models},
   volume = {8},
   year = {1990},
   annote = {predictive accuracy; validation; optimism; maximum likelihood}
}

@article{cop83reg,
   author = {Copas, J.B.},
   journal = "Journal of the Royal Statistical Society B",
   pages = {311-354},
   title = {Regression, prediction and shrinkage (with discussion)},
   volume = {45},
   year = {1983},
   annote = {shrinkage; validation; logistic model}
}

@article{cop87cro,
   author = {Copas, J.B.},
   journal = "Journal of the Royal Statistical Society B",
   pages = {175-183},
   title = {Cross--validation shrinkage of regression predictors},
   volume = {49},
   year = {1987},
   annote = {shrinkage; validation; calibration}
}


-- 
----------------------------------------------------------------------------
Frank E Harrell Jr			feh@biostat.mc.duke.edu
Associate Professor of Biostatistics
Division of Biometry                    Duke University Medical Center
From: thompson@atlas.socsci.umn.edu (T. Scott Thompson)
Newsgroups: sci.math.stat
Subject: FOUND: Phone number for SPSS Inc.
Date: 18 Dec 92 20:35:03 GMT
Reply-To: thompson@atlas.socsci.umn.edu
Organization: Economics Department, University of Minnesota

Many thanks to all of you who responded quickly to my request.  Here
is the relevant data:

Various Phone numbers reported for SPSS Inc. by sci.math.stat readers:

Sales:  (800) 543-2185       (This is the only one I verified personally.)
        (312) 329-2400
        (312) 329-3668 (Fax)

Support: (312) 329-3410
         (312) 329-3668 (Fax)

Development: (312) 329-3657

Unspecified: (312) 329-3500

I also discovered that at least one member of the SPSS technical
support team reads sci.math.stat.
--
T. Scott Thompson              email:  thompson@atlas.socsci.umn.edu
Department of Economics        phone:  (612) 625-0119
University of Minnesota        fax:    (612) 624-0209
From: bruhn@exaib (Peter Bruhn )
Newsgroups: sci.math.stat
Subject: Re: Durbin-Watson Statistic
Date: Tue, 15 Dec 92 08:17:38 MESZ
Organization: WU-Wien
Distribution: world
NNTP-Posting-Host: exaib.wu-wien.ac.at

In article <1992Dec14.193057.27625@anasaz> from [Mon, 14 Dec 1992 19:30:57 GMT] you wrote:
 > 
 > Does anyone have a program to compute the Durbin-Watson test statistic?
 > Thank you.

Rats does compute the Durbin-Watson test statistic.

Newsgroups: sci.math.stat
From: jhoste@kuju.claremont.edu (Jim Hoste)
Subject: looking for article on loaded dice
Keywords: probability, dice, loaded dice
Organization: Harvey Mudd College, Claremont, CA 91711
Date: Tue, 15 Dec 1992 23:34:05 GMT

Next semester I will be teaching an elementary probability class  
structured around the theme of games and gambling. I want to include some  
material on loaded dice. Surely someone has worked out the physics of  
rolling a die (in the shape of a cube) whose center of mass is not in the  
center of the die. What are the probablities of landing on the various  
faces as a function of the location of the center of mass? The same  
question can be asked for dice in the shape of other polyhedron,  
homogenious or not. 
	I am also interested in the following related question:
Can one create a die having n faces where the probability of landing on  
each of the faces is given in advance?  This is certainly true if *die* is  
interpreted fairly loosely. Somebody must have worked this out already.
	Can anyone recommend any good articles on these topics?
	I will summarize the replies that I receive.
	Thanks, Jim Hoste

ps I am also posting to:
	rec.gambling
	sci.math
	sci.physics
Newsgroups: sci.math.stat
From: simonb@extro.ucc.su.OZ.AU (Simon Blomberg)
Subject: Q:Discriminant Function Analysis in Systat
Keywords: statistics, discriminant function, multivariate, systat
Organization: Sydney University Computing Service, Sydney, NSW, Australia
Date: Wed, 16 Dec 1992 03:12:08 GMT

This post is on behalf of a friend (Diana Fisher, New South Wales
National Parks and Wildlife service, Australia).

Q. I am using discriminant function analysis to find out which
variables are best able to discriminate between 2 animal groups,
using Systat.

My problem is that not enough information is available on each variable
describing the animals to give a normal distribution; most are in the 
form:

    Dependent variable = 0 (Not having the characteristic)

     or                = 1 (Having the characteristic)

although some have more classes, e.g. body weight which is in 6 classes.

Does this matter? I have a suspicion that body weight is being chosen by
the analysis as one of the best discriminators because it is in 6, rather
than 2, classes, unlike the other variables. Could this be right? Does
internal rescaling prevent this problem? Cross-tabulations do not show
a large difference between the weights of the 2 animal groups, and
changing body weight to 2 classes (Heavy vs. light) reduces the importance
of body weight as a factor.

Thanks in advance,

Diana.

Please e-mail responses to me. I will post a summary of responses to
sci.math.stat. Thanks.

Simon.
-- 
Simon Blomberg                                   simonb@extro.ucc.su.OZ.AU
School of Biol. Sciences, A08
University of Sydney           We demand the right to stop to look even at
NSW   2006  Australia          lizards, who are nobody's property. -JBS Haldane 
Newsgroups: sci.math.stat
From: swknasri@nuscc.nus.sg (Sriram)
Subject: Range of std betas in MR
Organization: National University of Singapore
X-Newsreader: Tin 1.1 PL4
Date: Mon, 14 Dec 1992 06:16:02 GMT

What is the possible range of the standardized slope coeffs
in multiple regression? It is ofcourse  <=1 in absolute value
when there is one predictor but I remember getting slopes
outside that range in certain data with many predictors.


Sriram
From: bill@bessel.as.utexas.edu (William H. Jefferys)
Newsgroups: sci.math.stat
Subject: Re: looking for article on loaded dice
Date: 20 Dec 92 23:30:28 GMT
Organization: McDonald Observatory, University of Texas @ Austin

In article <168BFB8E5.R0264@vmcms.csuohio.edu> R0264@vmcms.csuohio.edu writes:

#See Letter to Editor re Kemp & Kemp, The American Statistician, August
#1992, Vol. 46, No 3, pp. 239-240.  Says  spots on most dice are
#countersunk, which throws the center of gravity off.  Also, since
#6 is opposite to 1, 5 to 2, etc., there is a predictable bias.

See also

  P.F. Fougere, "Maximum entropy calculations on a discrete 
  probability space," in G.J. Erickson and C.R. Smith, Eds.,
  _Maximum-Entropy and Bayesian Methods in Science and
  Engineering_, Vol. 1, 205-234 (1988). Dordrecht: Kluwer
  Academic Publishers.

  P.F. Fougere, "Maximum entropy calculations on a discrete 
  probability space: Predictions confirmed" in J. Skilling, Ed.,
  _Maximum-Entropy and Bayesian Methods_, 303-308 (1989).
  Dordrecht: Kluwer Academic Publishers.

This discusses an analysis of a long series of throws with
a (handmade in 19th century) set of dice by the Swiss
astronomer Wolf (of Wolf Sunspot Number fame). The tallies
were recorded and analyzed, an hypotheses about the shape
and irregularities of the dice suggested (in the first paper).
Later the actual dice were located and some of the predictions
confirmed. 

I don't know how good modern dice are, but the dice Wolf used
did show the spot effect, as well as two others.

Bill

Newsgroups: sci.math.stat
From: ken@psych.toronto.edu (Ken Seergobin)
Subject: TechPlot
Organization: Department of Psychology, University of Toronto
Date: Mon, 14 Dec 1992 18:40:47 GMT


Does anyone have any experience with a 'scientific' plotting
package called Techplot?  Any impressions would be welcome.
I am curious about the quality of output and the accuracy
of the statistics/math performed.

Thanks,
Ken

Newsgroups: sci.math.stat
From: erik@anasaz (Erik Schoenfeld)
Subject: Durbin-Watson Statistic
Organization: Anasazi, Inc. Phoenix, AZ, USA
Date: Mon, 14 Dec 1992 19:30:57 GMT


Does anyone have a program to compute the Durbin-Watson test statistic?
Thank you.
Newsgroups: sci.math.,sci.math.stat
From: Michael.Lowry@launchpad.unc.edu (Michael Lowry)
Subject: Complex Inequality?
Organization: University of North Carolina Extended Bulletin Board Service
Date: Sun, 13 Dec 1992 03:42:04 GMT

I'm trying to show the conditions for which the modulus (absolute value)
of the roots of 1-bx-c^2=0 are greater than one.  The roots are:

( b+Sqrt(b^2+4a) )/(-2a)       and       ( b-Sqrt(b^2+4a) )/(-2a)

from the quadratic formula.  In other words I must find the conditions
on b and a for which the roots lie outside the unit circle in the 
complex plane.  I'm not having much success.  Can anyone help?
I do have the answer from a reference which does not do the math:
       a + b < 1   ;    a - b < 1    ;   -1 < a < 1
This problem comes from the stationarity condition for a second order 
autoregressive model for a time series.

Thanks for any help,
Michael Lowry
Michael.Lowry@bbs.oit.unc.edu


--
   The opinions expressed are not necessarily those of the University of
     North Carolina at Chapel Hill, the Campus Office for Information
        Technology, or the Experimental Bulletin Board Service.
           internet:  laUNChpad.unc.edu or 152.2.22.80
From: rcj@lhdsy1.lahabra.chevron.com (R.C. Jones)
Newsgroups: sci.math.stat
Subject: Re:Statistics packages for IBM pc
Keywords: Minitab, etc.
Date: 15 Dec 92 17:57:24 GMT
Organization: Chevron Oil Field Research Co., La Habra, CA

I'm looking for a statistics/probability program for the IBM pc.
Any reccomendations? How to order and approx. how much?
Will be involved in an introductory college course in probability
and statistics. Thanks for any advice.


-- 
  |___________________________________________________________________| 
>>| Dik Jones, Earth Model Interpretation   Internet: rcj@Chevron.com |
  | Chevron Petroleum Technology Company.        Tel:  (310) 694-7056 | 
  | La Habra, California 90633-0446              Fax:  (310) 694-7063 |  
Newsgroups: sci.math.stat
From: R0264@vmcms.csuohio.edu
Subject: Re: Simple Odds on dice.
Organization: CSU
Date: Fri, 18 Dec 1992 20:08:13 GMT

In article <168C1D231.R0264@vmcms.csuohio.edu>
R0264@vmcms.csuohio.edu writes:
 
>
>In article <Russel_Mcauliffe.5w90@equinox.gen.nz>
>Russel_Mcauliffe@equinox.gen.nz (Russel Mcauliffe) writes:
>
>>
>>I have just been playing drinking games with a friend of mine and we had an
>>argument about the odds of wining [losing??!!], and I was wondering if
>>anyone could clarify the situation.
>>
>>The game was a very simple one (you don't need to be at all sober to play)
>>and it basically goes like this:-
>>
>>There are 3 die(dice). You call a number before throwing the die and however
>>many times that number comes up (out of the three die) you have to 'skull'
>>that many glasses. My friend reckoned that there was a 1 in 6 chance of
>>'skulling' but obviously that was completely wrong. No matter how I tried to
>>point out he was wrong, he wouldn't beleive me and as I was [am] quite drunk
>>I couldn't come up with a suitable arguement. What I would like to know is
>>the odds of throwing a single, a double and a triple of the number.
>>
>>Any written proof in my argument would be much appreciated.
>>Cheers!!!!!
>>RJ.
>Well, unless there is some trick that I don't see, P(just once) =
>(1/6)(5/6)(5/6); P(twice) = (1/6)(1/6)(5/6); P(thrice) = (1/6)(1/6)(1/6).
>These are mutually exclusive, so P(once or more) = 31/16.
>Phil, Cleveland State University.
OOPS! I missed a trick.  It should be p(once) = 3(1/6)(5/6)(5/6);
p(twice) = 3(1/6)(1/6)(5/6); and p(thrice) was ok.  So P(once or more)
= 91/216, quite a difference.  Also, and easier, p(none) = (5/6)(5/6)(5/6)
and p(one or more) = 1 - p(none).
Phil again.
Newsgroups: sci.math.stat