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  positive definiteness of matrix with complex entries, Sylvester criteria         


Author: Madhu
Date: Jan 16, 2007 12:58

I am developing an application that takes a correlation matrix (R) as
its input. R is a Hermitian matrix that has the correlations between a
set of complex Gaussian random variables.

If K is a matrix that has a set of complex Gaussian random variables, R
is defined as R=E(vec(K)*vec(K)^H), where K^H is hermitian of vec(K)
So R is a matrix of complex random variables.

Other properties of the matrices:
->entries of K are complex normal, (have 0 mean and unit variance)
->main diagonal entries of R are unity

The user types each entry for just the lower triangular matrix of R
(since R is Hermitian) through a GUI.

I need to ensure that the matrix R is positive definite. This is
because the R matrix is positive definite and I will be doing a
Cholesky decomposition on it.
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1 Comment
  Re: Multivariate optimization by solving one-dimensional problems (and using approximations)         


Author: Peter Spellucci
Date: Jan 16, 2007 09:59

In article <1168951067.558027.113150@v45g2000cwv.googlegroups.com>,
"andrea" yahoo.com> writes:
>Hi,
>
>In Bronstein/Semendjajew/Musio/M=FChlig (2000), Taschenbuch der
>Mathematik, p. 891, it is stated that the following algorithm can be
>used to find the minimum x* of the problem f(x) =3D min!, x \in R^n:
>
>1) Set x =3D x^1, where x_1 is some appropriate approximation for x*
>
>2) Solve for r=3D1,2,...,n the one-dimensional optimization problems
>
> g(a_r) =3D f(x_1^(k+1), ..., x_{r-1}^{k+1} + a_r,
||| either a "," here
or x_r^k instead of x_{r-1}^{k+1}
what is intended: minimization with respect to the r-th coordinate
>x_{r+1}^k,...,x_n^k) =3D min!, a_r \in R^n
>
> If a_r is a minimum or an approximation to the minimum of the r-th
>problem, set x_r^{k+1} =3D x_r^k + a_r. ...
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  Re: Bell shaped curves         


Author: mecej4
Date: Jan 16, 2007 08:54

Stig Holmquist wrote:
> The most common bell shaped curve is the normal or Gaussian but
> not all data forming a symmetrical bell shaped curve are normal.
>
> I wen to Google to search for other bell curves but found none.
> Is there a book discussing other bell curves and how to find
> their standard deviation from the mean?

Kendall's Advanced Theory of Statistics, Volume 1: Distribution Theory,
Oxford Univ. Press, ISBN 0 340 61430 7
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  Re: Appell Hypergeometric Function         


Author: Paul Abbott
Date: Jan 16, 2007 06:49

In article <1168899529.177303.316390@v45g2000cwv.googlegroups.com>,
"user923005" connx.com> wrote:
> OliveWork@gmail.com wrote:
>> I'm doing numerical evaluation of second kind Appell Hypergeometric
>> Function with two variables.
>>
>> Reference link:
>> http://mathworld.wolfram.com/AppellHypergeometricFunction...
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