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Subject: "matrix algebra"     Previous Topic | Next Topic
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Conferences The CTK Exchange College math Topic #577
Reading Topic #577
Jim
guest
Jul-06-06, 08:22 PM (EST)
 
"matrix algebra"
 
   I am trying to solve a matrix optimization problem.
Can anyone help in solving this?

I need to maximize |AZB|^2+|AZC|^2 with respect to the matrix Z with the restriction that Z should be diagonal.


A-row vector 1*N
Z N*N diagonal
B-col vector N*1
C-col vector N*1

All the elements are complex numbers. |.| indicates the magnitude of the complex number.

I think |AZB|^2+|AZC|^2 = |ABZ|^2+|ACZ|^2
since Z is diagonal.

thanks for your time
Jim.


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sfwc
Member since Jun-19-03
Jul-07-06, 07:34 AM (EST)
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1. "RE: matrix algebra"
In response to message #0
 
   >I need to maximize |AZB|^2+|AZC|^2 with respect to the
>matrix Z with the restriction that Z should be diagonal.
Are there any other restrictions? Currently this value may be made arbitrarily large. Let X be diagonal and such that k = |AXB|^2 + |AXC|^2 is nonzero. Then if Z = nX we have |AZB|^2 + |AZC|^2 = kn^2 which can be made as big as you like.

Thankyou

sfwc
<><


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Jim
guest
Jul-07-06, 07:13 PM (EST)
 
2. "RE: matrix algebra"
In response to message #1
 
   thanks for the reply.

I forgot to mention a trace constraint. Here is the complete problem.

I need to maximize |AZB|^2+|AZC|^2 with respect to the
matrix Z with the restriction that Z should be diagonal and trace(z)=1.

Is this problem solvable?
Is it possible to obtain an optimal matrix Z* in terms of A, B and C?

thanks
jim


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Jim
guest
Jul-09-06, 05:47 AM (EST)
 
3. "RE: matrix algebra"
In response to message #2
 
   I am basically interested in finding the column vector x that maximizes x'Ax subject to the constraint that x is unit norm.
where x' is transpose of x.


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