Matthew Knepley <knep...@gmail.com> writes: > On Thu, Sep 25, 2014 at 1:46 PM, Abhyankar, Shrirang G. <abhy...@mcs.anl.gov >> wrote: > >> You are right. The Jacobian for the power grid application is indeed >> non-symmetric. Is that a problem for your application? >> > > If you need a symmetric Jacobian, you can use the BC facility in > PetscSection, which eliminates the > variables completely. This is how the FEM examples, like ex12, work.
You can also use MatZeroRowsColumns() or do the equivalent transformation during assembly (my preference).
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