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Art Kendall
science forum beginner

Joined: 16 Jun 2005
Posts: 9

Posted: Wed Apr 05, 2006 1:38 am    Post subject: Re: multidimensional scaling clustering

You're welcome.

Art

bird wrote:
 Quote: Ark, Thank you so much for your help. I will keep looking the links you provide. Thank you again. -Kevin "Art Kendall" wrote: Doug Carroll and colleagues at Bell labs created extensions to the single matrix MDS (e.g., Joe Kruskal). George xxxx developed a method that found clusters and dimensions on the same run. The Classification Society Of North America is for people from all kinds of disciplines who are interested in MDS, clustering, etc. Biologists, Psychologists, statisticians, astronomers, zoologists, computer and information scientists, etc. If you go to http://www.classification-society.org/csna/csna.html to learn about the society click < mailing list > on the bottom left of the page or go to http://www.classification-society.org/csna/lists.html#class-l to learn about class-l This would be a good place to pose your questions. Art Art@DrKendall.org Social Research Consultants bird wrote: Thank you for your help. I read some books and I think I see some of your points now. I have just one more question. Suppose I have n objects, each has m features, then I actually have a matrix A(nxm). I want to use MDS to reduce the features to a p dimensional space, that's say I want a matrix B(nxp). The final configuration attained by MDS is actually a transformation T(mxp) telling me how to transform A to B. Is it right? Since it is a nonliear transformation, does B equal A x T?
science forum beginner

Joined: 11 Apr 2006
Posts: 1

Posted: Tue Apr 11, 2006 2:14 pm    Post subject: Re: JOHN CHIPMAN OWNER OF CHIPMAN RELOCATIONS UNITED VAN LINES MAYFLOWER CATON MOVING & STORAGE likes to make many harassing/harassment phone calls

arewehavingfunyetyes wrote:
 Quote: JOHN CHIPMAN OWNER OF CHIPMAN RELOCATIONS UNITED VAN LINES MAYFLOWER CATON MOVING & STORAGE likes to make many harassing/harassment phone calls JOHN CHIPMAN OWNER OF CHIPMAN UNITED VAN LINES likes to make many harassing/harassment phone calls to people and the old man sounds like he is off his meds he says my name is JOHN CHIPMAN OWNER OF CHIPMAN UNITED VAN LINES and i would like to buy you a cup of tea. you can hear the many harassing/harassment phone calls he is making from 510-337- & 510-337- @ http://tinyurl.com/pe67o United Van Lines Agent,Concord, CA 94520 Chipman Relocations, Alameda, CA 94501 moving boxes California Movers storage zoominfo.com

John Wants To Buy This Guy A Denny's \$1.99 Breakfast Special
David L. Wilson
science forum beginner

Joined: 31 May 2005
Posts: 37

Posted: Fri Apr 14, 2006 1:17 am    Post subject: Re: Free math software

"Evgeny Turchyn" <evgturchin@narod.ru> wrote in message
news:Xns97A440B26CF5Ftvn47ateleportcom@195.248.191.68...
 Quote: Hello, All! Can anyone recommend a good free math software for Windows with abilities compatible with those of Scilab or Maple - i.e having all basic mathematical capabilities: integration, plotting, built-in programming language etc. ? (Please do not offer Scilab.) What can one say about R for Windows? Is it good at such problems as numeric integrating, for instance?

R is designed for statistics work (it is an implementation of the S
statistics language).
I suggest you consider Maxima for what you are interested in doing.
http://maxima.sourceforge.net/
Rusty

Joined: 30 Apr 2005
Posts: 70

Posted: Sat Apr 15, 2006 9:03 am    Post subject: Re: Discover Medieval Romania /Vlad the Impaler/Dracula/ /www.medievaltours.ro

Medieval Tours wrote:
 Quote: br div align="center">

my browser never did support html

john2
David Langevin
science forum beginner

Joined: 16 Aug 2005
Posts: 9

 Posted: Fri May 05, 2006 1:00 am    Post subject: Re: not positive-definite covariance matrix Hi, When I look at your eigenvalues, I see one who is negative, and it mean that your matrix is not positive definite. At this point you have three way to solve your problem: 1) Check your data to see if you cannot pertubate one entry in your matrix to have a positive definite one 2) Or you can use hypersphere decomposition from your not positive definite matrix and obtain one who is close to your matrix but positive definite (see Monte Carlo methods in finance, Jackel for detail, chapter 6) 3) Or you can use spectral decomposition from your not positive definite matrix and obtain one who is close to your matrix but positive definite (see Monte Carlo methods in finance, Jackel for detail, chapter 6) I prefer spectral decomposition, because it more handy and easy to use than spectral decompostion. Also you don't have to solve an optimization problem. DL
Roger Stafford
science forum beginner

Joined: 14 Jun 2005
Posts: 5

Posted: Fri May 05, 2006 7:56 pm    Post subject: Re: not positive-definite covariance matrix

In article
<ellieandrogerxyzzy-0505061242480001@dialup-4.232.228.189.dial1.losangeles1.level3.net>,
ellieandrogerxyzzy@mindspring.com.invalid (Roger Stafford) wrote:

 Quote: I am very curious about your matrix d. You describe it as, "d is ... -----

Sorry about the duplications. They were not intentional.

(Remove "xyzzy" and ".invalid" to send me email.)
Roger Stafford
Gottfried Helms
science forum Guru

Joined: 24 Mar 2005
Posts: 301

 Posted: Fri May 05, 2006 8:14 pm    Post subject: Re: not positive-definite covariance matrix ANother approach, besides the already given ones, may be a SVD-decomposition. Since it is a covariance, it is symmetric and M = S D T = S D S' where D is diagonal. Then you could inspect D and see, whether you may apply rounding to zero for very small negative D. After that the cholesky-decomposition is C = S * D^(1/2) and M = C * C' THis way you may have more control over the numerical problems, and I think, Matlab should provide the tools to deal with this problem sensibly. Gottfried Helms
Jean-Marc Gulliet
science forum beginner

Joined: 28 May 2005
Posts: 38

Posted: Sun May 21, 2006 3:00 pm    Post subject: Re: Trig identity

Andrew Poelstra wrote:
 Quote: On 2006-05-20, Kaimbridge wrote: Borked Pseudo Mailed wrote: 1-cos(x) -------- = tan(x/2)^2 1+cos(x) 1-cos(x)^2 ---------- = ????? 1+cos(x)^2 Does anyone know what function this reduces to? I presume you mean a single function, in which case I don't think there is one. However, besides the ones that others have pointed out, some more equivalencies are: sin(x)^2 .5*sin(x)^2 2*sin(.5*x)^2*cos(.5*x)^2 ------------ = --------------- = -----------------------------, 2 - sin(x)^2 1 - .5*sin(x)^2 1 - 2*sin(.5*x)^2*cos(.5*x)^2 2 = -------------------------; tan(.5*x)^2 + cot(.5*x)^2 ~Kaimbridge~ Here's an equivilancy with the benifit of being easy to type: (cos(x) - 1)(cos(x) + 1) -------------------------- -(cos(x) - i)(cos(x) + i) Here is what I get with Mathematica 5.2

In[1]:=
TrigReduce[(1 - Cos[x]^2)/(1 + Cos[x]^2)]

Out[1]=
1 - Cos[2 x]
------------
3 + Cos[2 x]

HTH,
Jean-Marc
Tony Lance
science forum beginner

Joined: 18 May 2005
Posts: 30

astanoff@yahoo.fr
science forum beginner

Joined: 21 Oct 2005
Posts: 17

 Posted: Fri Jun 09, 2006 6:27 am    Post subject: Re: Normal distribution function with skew and kurtosis About the skew-normal distribution, you can have a look at : http://www.bus.lsu.edu/economics/faculty/chill/personal/aie/DeLuca.pdf v.a.
J.V.Ashby
science forum beginner

Joined: 10 Jun 2005
Posts: 12

Posted: Thu Jun 15, 2006 7:23 am    Post subject: Re: ANNOUNCE: comp.soft-sys.octave has been created

This may be of interest to some here.

john

The Big-8 Management Board wrote:

 Quote: The Big-8 Management Board has voted to create comp.soft-syst.octave. The group was created on 12 Jun 2006. NEWSGROUPS LINE: comp.soft-sys.octave GNU Octave, language for numerical computations. CHARTER: comp.soft-sys.octave General GNU Octave questions and its application to specific fields such as digital signal processing, digital communications, medical imaging, etc., as well as development issues such as bugs, fixes, workarounds, etc., in the main Octave kernel as well as developer- and user-supplied scripts (.m files) which extend Octave's functionality. The general issues include: * Addressing new user queries. * Exchange of source code in public domain, especially .m scripts. * Addressing the applications of GNU Octave in various fields. Usage specific in fields like Signal Processing: * Exchange of public domain source code to strengthen the signal processing part of GNU Octave. * Addressing the beginner to advanced queries regarding various signal processing related function available with GNU Octave, as built-in or as separate packages. Commercial Postings Commercial advertising related to Octave from software vendors, publishers, etc. will be permitted in a very limited fashion. Unwelcome posts Flames and other non-constructive criticism are harmful when directed to new readers. The octave group is meant to be a friendlier place on the net for beginners, intermediate, advanced users. Flames and other non-constructive criticism aimed at those seeking help are unwelcome. END CHARTER. PROPONENT: Himanshu Singh Chauhan
Himanshu Chauhan
science forum beginner

Joined: 15 Jun 2006
Posts: 2

Posted: Thu Jun 15, 2006 9:51 am    Post subject: Re: ANNOUNCE: comp.soft-sys.octave has been created

J.V.Ashby wrote:
 Quote: This may be of interest to some here. john

This group hasn't been added by google yet. I am, atleast, waiting for
them to do so.

I wasn't aware of this group earlier so I didn't cross post the RFDs
here. I am sorry for that.

--
----------------------------------------
Himanshu Chauhan
MCA (Final Year)
I.G. National Open University
Jaipur (India)

Mobile:(+91)-(98292)-(92757)
Web: http://members.lycos.co.uk/hschauhan
Email: hs.chauhan@gmail.com

"Education is what remains after one
has forgotten everything he learned
in school." -- A. Einstein.
----------------------------------------
Martin Eisenberg
science forum beginner

Joined: 11 May 2005
Posts: 28

Posted: Thu Jun 15, 2006 2:00 pm    Post subject: Re: ANNOUNCE: comp.soft-sys.octave has been created

Himanshu Chauhan wrote:

 Quote: This group hasn't been added by google yet. I am, atleast, waiting for them to do so.

What do you mean?

Martin

--
Quidquid latine scriptum sit, altum viditur.
Jean-Claude Arbaut
science forum Guru

Joined: 13 Jun 2005
Posts: 573

Posted: Thu Jun 15, 2006 2:03 pm    Post subject: Re: ANNOUNCE: comp.soft-sys.octave has been created

Martin Eisenberg wrote:
 Quote: Himanshu Chauhan wrote: This group hasn't been added by google yet. I am, atleast, waiting for them to do so. What do you mean? http://groups.google.com/group/sci.math.num-analysis

smna, yes, but not the new Octave group
Himanshu Chauhan
science forum beginner

Joined: 15 Jun 2006
Posts: 2

Posted: Thu Jun 15, 2006 3:47 pm    Post subject: Re: ANNOUNCE: comp.soft-sys.octave has been created

Martin Eisenberg wrote:
 Quote: Himanshu Chauhan wrote: This group hasn't been added by google yet. I am, atleast, waiting for them to do so. What do you mean? http://groups.google.com/group/sci.math.num-analysis Martin

Oh My fault in posting. Actually I meant "comp.soft-sys.octave" hasn't

Himanshu

--
----------------------------------------
Himanshu Chauhan
MCA (Final Year)
I.G. National Open University
Jaipur (India)

Mobile:(+91)-(98292)-(92757)
Web: http://members.lycos.co.uk/hschauhan
Email: hs.chauhan@gmail.com

"Education is what remains after one
has forgotten everything he learned
in school." -- A. Einstein.
----------------------------------------

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