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[Lapack] Inquiry about SLAED1.f


I have a question about the definition of 'INDXQ' in routine SLAED1.f.  It it 
so hard for me to comprehend what you mean by ''the permutation which 
separately sorts the two subproblems in D into ascending order''!

Let's take a simple example:  suppose D = diag([1 2 3 4]), u = Z = transpose([0 
1 1 0]), i.e. Q(in) = identity matrix and RHO = 1, what 'INDXQ' should be for 
matrix X = D + u*u^T = diag([1 2 3 4])  + transpose([0 1 1 0])*[0 1 1 0]?

Thank you very much for your attention and look forward to your reply!

Best regards,
Jie Wu, Jack
Graduate Student of Applied Physics
Physical Measurement and Control Group (
Stanford University
Email: wujie@Domain.Removed
Phone: 650-721-6265

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