>> 1. Replace the contents of PetscLinearSolver::print_converged_reason() by
>>
>> KSPConvergedReason reason;
>> KSPGetConvergedReason(_ksp, &reason);
>> libMesh::out << "Linear solver convergence/divergence reason: " <<
>> KSPConvergedReasons[reason] << std::endl;
>>
>> or similar.
>
> This sounds like a good idea, if you want to test it and send us the
> patch.
>
>> 2. Remove the this->clear() call from PetscNonlinearSolver::solve().
>> This prevents the _snes context pointer from being destroyed. In
>> PetscLinearSolver, the _ksp context pointer isn't destroyed either.
>
> I'm up for this unless anyone objects.
>
>> 3. Introduce PetscNonlinearSolver::print_converged_reason()
>> analogously to the linear solver, using the maintained _snes pointer.
>
> Sounds good.
Since there have been no further objections, here's a patch that does
all of the above. I have tested both linear (with example 9 for
instance) and nonlinear print_converged_reason()s, they're working
smoothly in the scope of my testing. Also, no negative side-effects
have occurred to me from keeping the _snes context alive.
You may perhaps commit the new
PetscLinearSolver::print_converged_reason before the rest, if you
prefer.
Roman
Index: include/solvers/petsc_nonlinear_solver.h
===================================================================
--- include/solvers/petsc_nonlinear_solver.h (revision 4219)
+++ include/solvers/petsc_nonlinear_solver.h (working copy)
@@ -95,7 +95,11 @@
const double, // Stopping tolerance
const unsigned int); // N. Iterations
-
+ /**
+ * Prints a useful message about why the latest nonlinear solve
+ * con(di)verged.
+ */
+ virtual void print_converged_reason();
private:
Index: include/solvers/nonlinear_solver.h
===================================================================
--- include/solvers/nonlinear_solver.h (revision 4219)
+++ include/solvers/nonlinear_solver.h (working copy)
@@ -105,6 +105,12 @@
const unsigned int) = 0; // N. Iterations
/**
+ * Prints a useful message about why the latest nonlinear solve
+ * con(di)verged.
+ */
+ virtual void print_converged_reason() { libmesh_not_implemented(); }
+
+ /**
* Function that computes the residual \p R(X) of the nonlinear system
* at the input iterate \p X.
*/
Index: src/solvers/petsc_linear_solver.C
===================================================================
--- src/solvers/petsc_linear_solver.C (revision 4219)
+++ src/solvers/petsc_linear_solver.C (working copy)
@@ -1437,62 +1437,9 @@
template <typename T>
void PetscLinearSolver<T>::print_converged_reason()
{
-#if PETSC_VERSION_LESS_THAN(2,3,1)
- libMesh::out << "This method is currently not supported "
- << "(but may work!) for Petsc 2.3.0 and earlier." << std::endl;
-#else
KSPConvergedReason reason;
KSPGetConvergedReason(_ksp, &reason);
-
- // KSP_CONVERGED_RTOL (residual 2-norm decreased by a factor of rtol, from 2-norm of right hand side)
- // KSP_CONVERGED_ATOL (residual 2-norm less than abstol)
- // KSP_CONVERGED_ITS (used by the preonly preconditioner that always uses ONE iteration)
- // KSP_CONVERGED_STEP_LENGTH
- // KSP_DIVERGED_ITS (required more than its to reach convergence)
- // KSP_DIVERGED_DTOL (residual norm increased by a factor of divtol)
- // KSP_DIVERGED_NAN (residual norm became Not-a-number likely do to 0/0)
- // KSP_DIVERGED_BREAKDOWN (generic breakdown in method)
-
- switch (reason)
- {
- case KSP_CONVERGED_RTOL:
- {
- libMesh::out << "Linear solver converged, relative tolerance reached." << std::endl;
- break;
- }
- case KSP_CONVERGED_ATOL:
- {
- libMesh::out << "Linear solver converged, absolute tolerance reached." << std::endl;
- break;
- }
-
- // Divergence
- case KSP_DIVERGED_ITS:
- {
- libMesh::out << "Linear solver diverged, max no. of iterations reached." << std::endl;
- break;
- }
- case KSP_DIVERGED_DTOL:
- {
- libMesh::out << "Linear solver diverged, residual norm increase by dtol (default 1.e5)." << std::endl;
- break;
- }
- case KSP_DIVERGED_NAN:
- {
- libMesh::out << "Linear solver diverged, residual norm is NaN." << std::endl;
- break;
- }
- case KSP_DIVERGED_BREAKDOWN:
- {
- libMesh::out << "Linear solver diverged, generic breakdown in the method." << std::endl;
- break;
- }
- default:
- {
- libMesh::out << "Unknown/unsupported con(di)vergence reason: " << reason << std::endl;
- }
- }
-#endif
+ libMesh::out << "Linear solver convergence/divergence reason: " << KSPConvergedReasons[reason] << std::endl;
}
Index: src/solvers/petsc_nonlinear_solver.C
===================================================================
--- src/solvers/petsc_nonlinear_solver.C (revision 4219)
+++ src/solvers/petsc_nonlinear_solver.C (working copy)
@@ -343,8 +343,6 @@
//Based on Petsc 2.3.3 documentation all diverged reasons are negative
this->converged = reason >= 0;
- this->clear();
-
STOP_LOG("solve()", "PetscNonlinearSolver");
// return the # of its. and the final residual norm.
@@ -353,7 +351,17 @@
+template <typename T>
+void PetscNonlinearSolver<T>::print_converged_reason()
+{
+ SNESConvergedReason reason;
+ SNESGetConvergedReason(_snes, &reason);
+ libMesh::out << "Nonlinear solver convergence/divergence reason: " << SNESConvergedReasons[reason] << std::endl;
+}
+
+
+
//------------------------------------------------------------------
// Explicit instantiations
template class PetscNonlinearSolver<Number>;
------------------------------------------------------------------------------
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