Hello,
I noticed that the neumann-poisson demo
(http://fenicsproject.org/documentation/dolfin/1.3.0/python/demo/documented/neumann-poisson/python/documentation.html)
fails when using a different solver, e.g. when replacing
solve(a == L, w)
with
solve(a == L, w,
solver_parameters = {'linear_solver': 'cg',
'preconditioner': 'ilu'})
The error that I'm getting with FEniCS 1.3 is:
$ python demo_neumann-poisson.py
Solving linear variational problem.
Solving linear system of size 4226 x 4226 (PETSc Krylov solver).
Traceback (most recent call last):
File "demo_neumann-poisson.py", line 68, in <module>
'preconditioner': 'ilu'})
File
"/home/nikratio/.local/FEniCS/lib/python2.7/site-packages/dolfin/fem/solving.py",
line 268, in solve
_solve_varproblem(*args, **kwargs)
File
"/home/nikratio/.local/FEniCS/lib/python2.7/site-packages/dolfin/fem/solving.py",
line 297, in _solve_varproblem
solver.solve()
RuntimeError:
***
-------------------------------------------------------------------------
*** DOLFIN encountered an error. If you are not able to resolve this issue
*** using the information listed below, you can ask for help at
***
*** fenics@fenicsproject.org
***
*** Remember to include the error message listed below and, if possible,
*** include a *minimal* running example to reproduce the error.
***
***
-------------------------------------------------------------------------
*** Error: Unable to solve linear system using PETSc Krylov solver.
*** Reason: Solution failed to converge in 2 iterations (PETSc reason
DIVERGED_INDEFINITE_PC, residual norm ||r|| = 1.541789e+19).
*** Where: This error was encountered inside PETScKrylovSolver.cpp.
*** Process: 0
***
*** DOLFIN version: 1.3.0
*** Git changeset:
***
-------------------------------------------------------------------------
Bug or user error?
Best,
Nikolaus
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