// ======================================================================
double MaxEigPowerMethod(const Operator& Op, const bool DiagonalScaling)
{
ML_Krylov *kdata;
double MaxEigen;
kdata = ML_Krylov_Create(GetML_Comm());
if (DiagonalScaling == false)
kdata->ML_dont_scale_by_diag = ML_TRUE;
else
kdata->ML_dont_scale_by_diag = ML_FALSE;
ML_Krylov_Set_PrintFreq(kdata, 0);
ML_Krylov_Set_ComputeNonSymEigenvalues(kdata);
ML_Krylov_Set_Amatrix(kdata, Op.GetML_Operator());
ML_Krylov_Solve(kdata, Op.GetML_Operator()->outvec_leng, NULL, NULL);
MaxEigen = ML_Krylov_Get_MaxEigenvalue(kdata);
ML_Krylov_Destroy(&kdata);
return(MaxEigen);
}
int main(int argc, char *argv[]){
ML *ml_object;
int i, N_grids = 3, N_levels;
double sol[129], rhs[129];
ML_Aggregate *agg_object;
ML_Operator *data;
ML_Krylov *kdata;
#ifdef ML_MPI
MPI_Init(&argc,&argv);
#endif
for (i = 0; i < 129; i++) sol[i] = 0.;
for (i = 0; i < 129; i++) rhs[i] = 2.;
ML_Create (&ml_object, N_grids);
ML_Init_Amatrix (ml_object, 0, 129, 129, NULL);
ML_Set_Amatrix_Getrow(ml_object, 0, Poisson_getrow, NULL, 129);
ML_Set_Amatrix_Matvec(ml_object, 0, Poisson_matvec);
ML_Set_PrintLevel(10);
ML_Aggregate_Create(&agg_object);
ML_Aggregate_Set_MaxCoarseSize(agg_object,1);
N_levels = ML_Gen_MGHierarchy_UsingAggregation(ml_object, 0,
ML_INCREASING, agg_object);
/******** Begin code to set a Jacobi smoother ******
ML_Gen_Smoother_Jacobi(ml_object, ML_ALL_LEVELS, ML_PRESMOOTHER, 1, ML_DEFAULT);
******** End code to set a Jacobi smoother ******/
/******** Begin code to set a user-defined smoother ******/
ML_Get_Amatrix(ml_object, 0, &data);
ML_Set_Smoother(ml_object, 0, ML_BOTH, data, user_smoothing,"mine");
ML_Get_Amatrix(ml_object, 1, &data);
ML_Set_Smoother(ml_object, 1, ML_BOTH, data, user_smoothing,"mine");
ML_Get_Amatrix(ml_object, 2, &data);
ML_Set_Smoother(ml_object, 2, ML_BOTH, data, user_smoothing,"mine");
ML_Gen_Solver (ml_object, ML_MGV, 0, N_levels-1);
/* This example uses an internal CG solver within ML */
/* ML has limited Krylov methods support. It is intended */
/* that ML be used with another package that supplies */
/* more sophisticated Krylov solver options (such as those */
/* found in the Trilinos or Aztec packages. */
kdata = ML_Krylov_Create(ml_object->comm);
ML_Krylov_Set_PrintFreq( kdata, 1 );
ML_Krylov_Set_Method(kdata, ML_CG);
ML_Krylov_Set_Amatrix(kdata, &(ml_object->Amat[0]));
ML_Krylov_Set_PreconFunc(kdata, ML_MGVSolve_Wrapper);
ML_Krylov_Set_Precon(kdata, ml_object);
ML_Krylov_Set_Tolerance(kdata, 1.e-7);
ML_Krylov_Solve(kdata, 129, rhs, sol);
ML_Krylov_Destroy( &kdata );
ML_Aggregate_Destroy(&agg_object);
ML_Destroy(&ml_object);
/******** End code to set a user-defined smoother ******/
printf("answer is %e %e %e %e %e\n",sol[0],sol[1],sol[2],sol[3],sol[4]);
#ifdef ML_MPI
MPI_Finalize();
#endif
exit(EXIT_SUCCESS);
}