Hello everyone,
I am working on a code for time dependent simulation. In the part of code I
have an error after a certain number of time steps for a large size
problem. The error occurs when it is calculating the k1 coefficient of
implicit Runge Kutta method by solving system of equations using
SolverBicgstab. I have set the maximum number of iterations to 1000000 and
abortion criteria 1e-12.
Following is the part where the code fails:
SolverControl solver_control
(parameters.maximum_number_of_iteration_steps, parameters.abort_criterion *
system_rhs_k1.l2_norm());
SolverBicgstab<> bicgstab (solver_control);
PreconditionJacobi<> preconditioner;
preconditioner.initialize(system_matrix_k1, 1.2);
bicgstab.solve (system_matrix_k1, k1_update, system_rhs_k1, preconditioner);
In the error message I have following:
----------------------------------------------------
Exception on processing:
--------------------------------------------------------
An error occurred in line <495> of file
</home/sfb814/spack/opt/spack/linux-ubuntu16-x86_64/gcc-5.4.0/dealii-develop-mlfap6oyiyr5ng6a5ticxjq665eem5vd/include/deal.II/lac/solver_bicgstab.h>
in function
void dealii::SolverBicgstab<VectorType>::solve(const MatrixType&,
VectorType&, const VectorType&, const PreconditionerType&) [with MatrixType
= dealii::SparseMatrix<double>; PreconditionerType =
dealii::PreconditionJacobi<>; VectorType = dealii::Vector<double>]
The violated condition was:
state.state == SolverControl::success
Additional information:
Iterative method reported convergence failure in step 1. The residual in
the last step was nan.
This error message can indicate that you have simply not allowed a
sufficiently large number of iterations for your iterative solver to
converge. This often happens when you increase the size of your problem. In
such cases, the last residual will likely still be very small, and you can
make the error go away by increasing the allowed number of iterations when
setting up the SolverControl object that determines the maximal number of
iterations you allow.
The other situation where this error may occur is when your matrix is not
invertible (e.g., your matrix has a null-space), or if you try to apply the
wrong solver to a matrix (e.g., using CG for a matrix that is not symmetric
or not positive definite). In these cases, the residual in the last
iteration is likely going to be large.
--------------------------------------------------------
Also when I tried it in the debug mode:
-------------------------------------------------------------------------------------------
Time step 250
at t=50
ADAPTIVE GRID REFINEMENT STEP: 1
Adaptive refining of grid...
Completed
Number of active cells: 46792
Number of degrees of freedom for the temperature: 22515
Number of degrees of freedom for the Parameters k of the implicit
Runge-Kutta method: 22515
Calculate k2 in parallel with shared memory...
Time for assembling system of equations for k2: 0.911958 seconds
Solving system of equations for k2...
Time for solving systems of equations: 0.0781541 seconds
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.58716 seconds
Solving system of equations...
Time for solving systems of equations: 0.158167 seconds
L2 Norm der rechten Seite nach der 1. Newton Raphson Iteration: 0.140345
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.61191 seconds
Solving system of equations...
Time for solving systems of equations: 0.169431 seconds
L2 Norm der rechten Seite nach der 2. Newton Raphson Iteration: 4.58376e-07
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.60747 seconds
Solving system of equations...
Time for solving systems of equations: 0.166696 seconds
L2 Norm der rechten Seite nach der 3. Newton Raphson Iteration: 3.84739e-14
Number of Newton Raphson iterations in the current time step: 3
Number of integration points enclosed by the heat source respectively beam:
749589
Current position of the beam: x: -0.031 y: 0 z: -0.0034
Writing results to output file...
Completed
Time step 251
at t=50.2
Deposition of the next powder layer...
Deposition of the next powder layer COMPLETED
ADAPTIVE GRID REFINEMENT STEP: 1
Adaptive refining of grid...
Completed
Number of active cells: 48416
Number of degrees of freedom for the temperature: 24965
Number of degrees of freedom for the Parameters k of the implicit
Runge-Kutta method: 24965
Calculate k2 in parallel with shared memory...
Time for assembling system of equations for k2: 0.914275 seconds
Solving system of equations for k2...
Time for solving systems of equations: 0.10148 seconds
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 2.21326 seconds
Solving system of equations...
Time for solving systems of equations: 0.145032 seconds
L2 Norm der rechten Seite nach der 1. Newton Raphson Iteration: 1.18614e+06
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.71319 seconds
Solving system of equations...
Time for solving systems of equations: 0.7223 seconds
L2 Norm der rechten Seite nach der 2. Newton Raphson Iteration: 8.3161
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.71675 seconds
Solving system of equations...
Time for solving systems of equations: 3.78979 seconds
L2 Norm der rechten Seite nach der 3. Newton Raphson Iteration: 5.42624
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.70202 seconds
Solving system of equations...
Time for solving systems of equations: 3.06816 seconds
L2 Norm der rechten Seite nach der 4. Newton Raphson Iteration: 10.2496
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.68715 seconds
Solving system of equations...
Time for solving systems of equations: 8.42527 seconds
L2 Norm der rechten Seite nach der 5. Newton Raphson Iteration: 8.33079
Assembling system of equations in parallel with shared memory...
Time for building up the system matrix and the vector of the right hand
side: 1.71263 seconds
Solving system of equations...
--------------------------------------------------------
An error occurred in line <541> of file
</home/sfb814/spack/var/spack/stage/dealii-develop-mlfap6oyiyr5ng6a5ticxjq665eem5vd/dealii/include/deal.II/lac/vector.templates.h>
in function
dealii::Vector<Number>::real_type dealii::Vector<Number>::l2_norm()
const [with Number = double; dealii::Vector<Number>::real_type = double]
The violated condition was:
dealii::numbers::is_finite(scale*std::sqrt(sum))
Additional information:
In a significant number of places, deal.II checks that some
intermediate value is a finite number (as opposed to plus or minus
infinity, or NaN/Not a Number). In the current function, we encountered a
number that is not finite (its value is (nan,0) and therefore violates the
current assertion).
This may be due to the fact that some operation in this function created
such a value, or because one of the arguments you passed to the function
already had this value from some previous operation. In the latter case,
this function only triggered the error but may not actually be responsible
for the computation of the number that is not finite.
There are two common cases where this situation happens. First, your code
(or something in deal.II) divides by zero in a place where this should not
happen. Or, you are trying to solve a linear system with an unsuitable
solver (such as an indefinite or non-symmetric linear system using a
Conjugate Gradient solver); such attempts oftentimes yield an operation
somewhere that tries to divide by zero or take the square root of a
negative value.
In any case, when trying to find the source of the error, recall that the
location where you are getting this error is simply the first place in the
program where there is a check that a number (e.g., an element of a
solution vector) is in fact finite, but that the actual error that computed
the number may have happened far earlier. To find this location, you may
want to add checks for finiteness in places of your program visited before
the place where this error is produced.One way to check for finiteness is
to use the 'AssertIsFinite' macro.
Stacktrace:
-----------
#0
/home/sfb814/spack/opt/spack/linux-ubuntu16-x86_64/gcc-5.4.0/dealii-develop-mlfap6oyiyr5ng6a5ticxjq665eem5vd/lib/libdeal_II.g.so.8.5.0-pre:
dealii::Vector<double>::l2_norm() const
#1 ./Nonlinear_Heat_Transfer: dealii::SolverControl::State
dealii::SolverBicgstab<dealii::Vector<double>
>::start<dealii::SparseMatrix<double> >(dealii::SparseMatrix<double> const&)
#2 ./Nonlinear_Heat_Transfer: void
dealii::SolverBicgstab<dealii::Vector<double>
>::solve<dealii::SparseMatrix<double>,
dealii::PreconditionJacobi<dealii::SparseMatrix<double> >
>(dealii::SparseMatrix<double> const&, dealii::Vector<double>&,
dealii::Vector<double> const&,
dealii::PreconditionJacobi<dealii::SparseMatrix<double> > const&)
#3 ./Nonlinear_Heat_Transfer:
NonlinearHeatTransfer<3>::assemble_and_solve_system_in_parallel_with_shared_memory()
#4 ./Nonlinear_Heat_Transfer: NonlinearHeatTransfer<3>::run()
#5 ./Nonlinear_Heat_Transfer: main
--------------------------------------------------------
Its clear that at t 50.2 sec I have some problem with the system of
equation leading to l2 residual norm to increase.
I believe the source of failure is in the assert check in SolverBicgstab.h
with the L2 residual norm:
// in case of failure: throw exception
AssertThrow(state.state == SolverControl::success,
SolverControl::NoConvergence (state.last_step, state.last_residual));
Could someone help in how to debug such a case and solve it?
Thanks in advance.
Regards,
Vinayak Gholap
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