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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. 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: [email protected] tel: +64 (0)9 923 4611
