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[Murtazo Nazarov <question108259@xxxxxxxxxxxxxxxxxxxxx>]

Question #108259 on DOLFIN changed:
https://answers.launchpad.net/dolfin/+question/108259

    Status: Answered => Solved

Murtazo Nazarov confirmed that the question is solved:
Yes, it seems hypre in my solver does not converge only in the first
iteration. Before it was just a warning, but with the latest dolfin it
stoped since it is assumed that it is an error.

Here I made a test for the same problem using the following lines:

   solver = KrylovSolver("gmres")
   solver.parameters["monitor_convergence"] = True
   solver.parameters["error_on_nonconvergence"] = False
..

"Old" dolfin gives:
....
Applying boundary conditions to linear system.
Applying boundary conditions to linear system.
Solving linear system of size 4184 x 4184 (PETSc Krylov solver).
  0 KSP preconditioned resid norm 2.663347782311e+02 true resid norm 1.371810197831e+01 ||Ae||/||Ax|| 7.817835153984e+08
*** Warning: Krylov solver did not converge (PETSc reason -4).
PETSc Krylov solver (gmres, hypre) failed to converge in 0 iterations.
...

and the latest dolfin gives:

Applying boundary conditions to linear system.
Applying boundary conditions to linear system.
Solving linear system of size 4184 x 4184 (PETSc Krylov solver).
  0 KSP preconditioned resid norm 6.346755394553e+02 true resid norm 3.269022479529e+01 ||Ae||/||Ax|| 3.675021072956e+08
*** Warning: Krylov solver did not converge (PETSc reason -4).
PETSc Krylov solver (gmres, hypre) failed to converge in 0 iterations.

It happened because of the luck of stabilization in startup.

It is nice to know about the latest flags in the parameter list for the
Krylov solver.

murtazo

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