nonsymmetric dynamics

create the preconditioner
ML_Epetra::MultiLevelPreconditioner * MLPrec =
new ML_Epetra::MultiLevelPreconditioner(*A, MLList, true);
// visualize the effect of the ML preconditioner on a
// random vector. We ask for 10 multilevel cycles
MLPrec->VisualizeCycle(10);
// visualize the effect of each level’s smoother on a
// random vector. We ask for 5 steps of presmoothers,
// and 1 step of postsmoother
MLPrec->VisualizeSmoothers(5,1);
(File ml_viz.cpp contains the compilable code.) We note that the parameters must be set
before calling ComputePreconditioner(). See also Section 6.4.12 for the requirements on
the coordinates vectors. Results will be written in the following files:
• before-presmoother-eqX-levelY.vtk contains the random vector before the application
of the presmoother, for equation X at level Y;
• after-presmoother-eqX-levelY.vtk contains the random vector after the application
of the presmoother, for equation X at level Y;
• before-postsmoother-eqX-levelY.vtk contains the random vector before the application
of the postsmoother, for equation X at level Y;
• after-postsmoother-eqX-levelY.vtk contains the random vector after the application
of the postsmoother, for equation X at level Y;
• before-cycle-eqX-levelY.vtk contains the random vector before the application of
the MLcycle, for equation X at the finest level;
• after-cycle-eqX-levelY.vtk contains the random vector after the application of the
ML cycle, for equation X at finest level.
6.8 Print the Computational Stencil for a 2D Cartesian Grid
Method PrintStencil2D() can be used to print out the computational stencil for problems
defined on 2D Cartesian grids, if the nodes numbering follows the x-axis. The following
fragment of code shows the use of this method:
int Nx = 16; // nodes along the x-axis
int Ny = 32; // nodes along the y-axis
int NodeID = -1; // print the stencil for this node
int EquationID = 0; // equation 0, useful for vector problems
// MLPrec is a pointer to an already created
// ML_Epetra::MultiLevelPreconditioner
MLPrec->PrintStencil2D(Nx,Ny,NodeID, EquationID);
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