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hi, I have a Jacobian matrix created using DMCreateMatrix(). What would be the best way to add extra nonzero entries into it? I'm guessing that DMCreateMatrix() allocates the storage so the nonzero structure can't really be easily modified.
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<meta charset="UTF-8"></head><body><pre style="font-family: sans-serif; font-size: 100%; white-space: pre-wrap; word-wrap: break-word">hi,
I have a Jacobian matrix created using DMCreateMatrix(). What would be
the best way to add extra nonzero entries into it?
I'm guessing that DMCreateMatrix() allocates the storage so the nonzero
structure can't really be easily modified. Would it be a case of
creating a new matrix, copying the nonzero entries from the original one
and then adding the extra ones, before calling MatSetUp() or similar? If
so, how exactly would you copy the nonzero structure from the original
matrix?
Background: the flow problem I'm solving (on a DMPlex with finite volume
method) has complex source terms that depend on the solution (e.g.
pressure), and can also depend on other source terms. A simple example
is when fluid is extracted from one location, with a pressure-dependent
flow rate, and some of it is then reinjected in another location. This
can result in poor nonlinear solver convergence. I think the reason is
that there are effectively missing Jacobian entries in the row for the
reinjection cell, which should have an additional dependence on the
solution in the cell where fluid is extracted.
- Adrian
--
Dr Adrian Croucher
Senior Research Fellow
Department of Engineering Science
Waipapa Taumata Rau / University of Auckland, New Zealand
email: a.croucher@auckland.ac.nz
tel: +64 (0)9 923 4611
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