Hoang Giang Bui <[email protected]> writes: > One more question I like to ask, which is more on the performance of the > solver. That if I have a coupled problem, says the point block is [u_x u_y > u_z p] in which entries of p block in stiffness matrix is in a much smaller > scale than u (p~1e-6, u~1e+8), then AMG with hypre in PETSc still scale?
You should scale the model (as Barry says). But the names of your variables suggest that the system is a saddle point problem, in which case there's a good chance AMG won't work at all. For example, BoomerAMG produces a singular preconditioner in similar contexts, such that the preconditioned residual drops smoothly while the true residual stagnates (the equations are not solved at all). So be vary careful if you think it's "working".
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