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

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Nicolas Bonneel

Posts: 6
Registered: 4/23/13
Re: Nx2N lapped orthogonal transform
Posted: Aug 20, 2013 2:31 PM
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On 8/20/2013 3:45 AM, Robin Chapman wrote:
> On 19/08/2013 19:04, Nicolas Bonneel wrote:
>> On 8/19/2013 12:34 AM, James Dow Allen wrote:
>>> 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?

>> by direct computation, AB=BA=0 and A^2+B^2=Id, right?

> No

ok, but why not ?
Noting the matrix above M, I just did M^T.M=Id and directly computed the
matrix multiplication per block.

Nicolas Bonneel

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