Proof of (8.21)

Dear Sigurd,

the proof of eq. (8.21) is not clear to me. What does the tilde variables
really mean? It seems that they denote the SVD of G^{-1} but, if this is the
case, why not write this as G^{-1} = VS^{-1}U^H ?
However, this means that \Delta should be chosen in a different way, namely,
\Delta = V J V^H, where J is a matrix with ones along the anti-diagonal.

Yours sincerely,

-- 
____________________________________
Magnus Jansson
S3-Automatic Control
Royal Institute of Technology (KTH)
S-100 44 Stockholm
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Email:	magnusj@s3.kth.se