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MathGroup Archive 2005

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sporadic failure of SingularValueDecomposition[] in Mathematica 5.2

  • To: mathgroup at smc.vnet.net
  • Subject: [mg60563] sporadic failure of SingularValueDecomposition[] in Mathematica 5.2
  • From: John Sidles <sidles at u.washington.edu>
  • Date: Tue, 20 Sep 2005 05:19:38 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Dear Mathgroup folks

Has anyone else encountered sporadic failure of  
SingularValueDecomposition[]?

Running Mathematica 5.2 under OS X, our UW Quantum System Engineering (QSE)  
group
is finding that SVD fails completely, for well-conditioned Hermitian  
input
matrices, about one time in 1000.

A test matrix for which SingularValueDecomposition[] fails completely
can be found in this directory:

     http://faculty.washington.edu/sidles/mma_svd_failure_example/

The directory contains the following files:

     mma_svd_matrix.m  (* a 90x90 Hermitian matrix for which SVD  
fails *)
     mma_svd_failure_example.pdf   (* notebook demonstrating the  
failure *)
     mma_svd_failure_example.pdf   (* PDF of above *)

It would be a big help if someone running Unix or Windows would
report on whether this matrix fails for them.

Thanks in advance !!!  John Sidles


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