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Subject: factorization of sparse, complex, symmetric, singular matrix From: Herwig Date: 20 Jan, 2014 22:14:07 Message: 1 of 8 
I use Ansys to build FE matrices using the Shell281 element (it *must* be this specific element). I then export the matrices from Ansys and import them into Matlab, where they are coupled with boundary element matrices. The solution of the overall system requires an iterative solver (GMRES) which of course works best if the system is preconditioned. So, as the title suggests, I need to factorize an FE matrix that is sparse, complex, symmetric and singular : 
Subject: factorization of sparse, complex, symmetric, singular matrix From: Bruno Luong Date: 21 Jan, 2014 08:20:11 Message: 2 of 8 
>. Of course, the next step is to try chol() and ichol() but these surrender quickly due to the properties of my matrix (error: Encountered nonpositive pivot). 
Subject: factorization of sparse, complex, symmetric, singular matrix From: Herwig Date: 21 Jan, 2014 09:21:08 Message: 3 of 8 
Oops, I must have overlooked that Hermitian requirement of chol() ! 
Subject: factorization of sparse, complex, symmetric, singular matrix From: Torsten Date: 21 Jan, 2014 13:39:08 Message: 4 of 8 
"Herwig " <herwig.peters@unsw.edu.au> wrote in message <lble64$29i$1@newscl01ah.mathworks.com>... 
Subject: factorization of sparse, complex, symmetric, singular matrix From: Herwig Date: 22 Jan, 2014 01:01:09 Message: 5 of 8 
Thanks Torsten, that does look interesting indeed. I've requested a copy of the code from the authors. I'll report back how it went in a couple of days. 
Subject: factorization of sparse, complex, symmetric, singular matrix From: Bruno Luong Date: 22 Jan, 2014 08:01:08 Message: 6 of 8 
"Herwig " <herwig.peters@unsw.edu.au> wrote in message <lbk73f$oll$1@newscl01ah.mathworks.com>... 
Subject: factorization of sparse, complex, symmetric, singular matrix From: Herwig Date: 22 Jan, 2014 10:01:08 Message: 7 of 8 
1) "In the end, the aim is to fit bigger models into memory." 
Subject: factorization of sparse, complex, symmetric, singular matrix From: Bruno Luong Date: 22 Jan, 2014 19:59:09 Message: 8 of 8 
"Herwig " <herwig.peters@unsw.edu.au> wrote in message <lbo4t4$q54$1@newscl01ah.mathworks.com>... 
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