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Re: Covariance Matrices in RhoCandidates [message #16344 is a reply to message #16343]

Wed, 16 April 2014 19:37

SHenssler
Messages: 13
Registered: March 2014
Location: FZ Jülich

occasional visitor

From: *customers.d1-online.com

Hello Stefano,

positive semi definite does not mean that there cannot be negative values.
The Definition says, that any vector y multiplied in the way: y^t * C * y,
where C is the Covariance Matrix, must result in a value greater or equal to zero.
In a way that is the proof, that the Chi-Square value ( y^t * C^-1 * y ) is always positive.
Or rather, if C is not positive semi definite, then it cannot ne guaranteed that the Chi Square value is positive.
It is a mathematical property that every Covarince Matrix Must have.

Cheers
Simon

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[Message index]

		Covariance Matrices in RhoCandidates By: SHenssler on Tue, 25 March 2014 14:51
		Re: Covariance Matrices in RhoCandidates By: Ralf Kliemt on Tue, 25 March 2014 16:24
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Tue, 25 March 2014 16:43
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Tue, 25 March 2014 17:22
		Re: Covariance Matrices in RhoCandidates By: Ralf Kliemt on Tue, 25 March 2014 17:39
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Tue, 25 March 2014 22:13
		Re: Covariance Matrices in RhoCandidates By: Ralf Kliemt on Wed, 26 March 2014 08:01
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Wed, 26 March 2014 09:26
		Re: Covariance Matrices in RhoCandidates By: Ralf Kliemt on Fri, 28 March 2014 13:35
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Thu, 03 April 2014 12:14
		Re: Covariance Matrices in RhoCandidates By: Ralf Kliemt on Fri, 04 April 2014 16:09
		Re: Covariance Matrices in RhoCandidates By: StefanoSpataro on Fri, 04 April 2014 16:17
		Re: Covariance Matrices in RhoCandidates By: Ralf Kliemt on Fri, 04 April 2014 16:21
		Re: Covariance Matrices in RhoCandidates By: StefanoSpataro on Wed, 16 April 2014 18:01
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Wed, 16 April 2014 19:37
		Re: Covariance Matrices in RhoCandidates By: StefanoSpataro on Wed, 16 April 2014 22:02
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Thu, 17 April 2014 10:08
		Re: Covariance Matrices in RhoCandidates By: StefanoSpataro on Thu, 17 April 2014 10:13
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Thu, 17 April 2014 13:10
		Re: Covariance Matrices in RhoCandidates By: StefanoSpataro on Thu, 17 April 2014 13:43
		Re: Covariance Matrices in RhoCandidates By: SHenssler on Thu, 17 April 2014 13:58

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