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From: tinne123 on 26 Apr 2010 18:28
Hi Folks,

I would be thankful for some hints how to solve a system of matrix equations some elements of which are restricted.

B, C, E, Q - known (estimated) matrices, Q is symmetric
A - unknown matrix, but some elements are restricted to be known
A = [ ?, ?, ?; ?, ?, ?; ?, known, known]
M - unknown matrix

I have not quite any idea, how to write this system so that some elements in the A matrix are set unknown and which Matlab commands shall I use to solve for A (and M)?

(1) A * B = C
(2) A A' = Q
(3) M' M = I (identity matrix)
(4) A * E = M

I hope there is somebody out there for whom this is a funny easy problem to solve. Thanks for helping!!!!

Nadja
From: tinne123 on 26 Apr 2010 19:15
"tinne123 " <nastanova(a)yahoo.co.uk> wrote in message <hr5425$dbu$1(a)fred.mathworks.com>...
> Hi Folks,
>
> I would be thankful for some hints how to solve a system of matrix equations some elements of which are restricted.
>
> B, C, E, Q - known (estimated) matrices, Q is symmetric
> A - unknown matrix, but some elements are restricted to be known
> A = [ ?, ?, ?; ?, ?, ?; ?, known, known]
> M - unknown matrix
>
> I have not quite any idea, how to write this system so that some elements in the A matrix are set unknown and which Matlab commands shall I use to solve for A (and M)?
>
> (1) A * B = C
> (2) A A' = Q
> (3) M' M = I (identity matrix)
> (4) A * E = M
>
> I hope there is somebody out there for whom this is a funny easy problem to solve. Thanks for helping!!!!

Hi there, sorry for a typo:
The C matrix is known, but some elements are restricted to zero:

C = [known, 0, 0; known, known, known; known, known, known]
From: Greg Heath on 26 Apr 2010 23:18
On Apr 26, 6:28 pm, "tinne123 " <nastan...(a)yahoo.co.uk> wrote:
> Hi Folks,
>
> I would be thankful for some hints how to solve a system of matrix equations some elements of which are restricted.
>
> B, C, E, Q - known (estimated) matrices, Q is symmetric
> A - unknown matrix, but some elements are restricted to be known
> A = [ ?, ?, ?; ?, ?, ?; ?, known, known]
> M - unknown matrix
>
> I have not quite any idea, how to write this system so that some elements in the A matrix are set unknown and which Matlab commands shall I use to solve for A (and M)?
>
> (1) A * B = C
> (2) A A' = Q
> (3) M' M = I (identity matrix)
> (4) A * E = M
>
> I hope there is somebody out there for whom this is a funny easy problem to solve. Thanks for helping!!!!

There is no size, shape information.

For a start make the transformation

A = [ D F]

Then substitute and rearrange to have all terms with D and M
on the LHS.

Hope this helps.

Greg
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