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Topic: Nx2N lapped orthogonal transform
Replies: 13   Last Post: Sep 12, 2013 7:38 PM

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James Dow Allen

Posts: 15
Registered: 12/14/08
Re: Nx2N lapped orthogonal transform
Posted: Sep 3, 2013 5:32 AM
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James Dow Allen <gmail@jamesdowallen.nospam> might have writ, in
news:XnsA22175B33BFDDjamesdowallen@178.63.61.175:

> Let
> ( A B 0 )
> ( 0 A B )
> ( B 0 A )
> be a 3Nx3N real matrix with A,B,0 each NxN and 0 an all-zeros matrix.
>
> What is the necessary and sufficient condition for that matrix to be
> orthogonal, i.e. that its transpose also be its inverse?
>
> This problem statement can be considered ambiguous.
> *But if you derive a good parametric form for (A B) you will know it.*
>
> (I already "know the answer." I post from curiosity: Is this a VERY easy
> problem, or just an easy problem?)


James Dow Allen <gmail@jamesdowallen.nospam> might have writ, in
news:XnsA2236C8E3E26Ajamesdowallen@178.63.61.175:

> I found it fruitful to introduce M = A + B; S = A - B

I will bump my own thread one time. I'm certain that this is an easy
problem for many sci.math'ers, especially with the hint.
The solution involves a particular type of matrix which might lead to an
interesting discussion.

James Dow Allen



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