[petsc-users] about FD Jacobian for the new DAE solver

On Thu, 29 Apr 2010 21:08:38 +, Li, Zhisong (lizs) lizs at mail.uc.edu wrote: Hi, Last time I was suggested by Jed using the DAE solver to build my nonlinear CFD code based on TS. For incompressible N-S equations, I think it's difficult to derive the analytical Jacobian formulation,

[petsc-users] about FD Jacobian for the new DAE solver

On Thu, 29 Apr 2010 22:28:39 +, Li, Zhisong (lizs) lizs at mail.uc.edu wrote: I wonder if you mean the finite element method here. I am only planning FDM or FVM for my work. Actually we don't have any polynomial in incompressible N-S equations. As Matt says, the convection term is

[petsc-users] zero diagonals

No, nor is there likely a reason you would want to do that. It is practically mathematically meaningless. You can write a routine that loops over each local row, checks if the row has zero diagonal, keep the list of these rows and then call MatSetValues() for the diagonals of those

[petsc-users] about snes and finite difference jacobian approximations

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