tag.iters() and tag.error() show zero.

[p ding]

Dear friends:
I do not know why tag.iters() and tag.error() both give "0". that means it performed 0 iteration. But the results is changing.
I am solve the diffusion problem with 250,000 3D unstructured mesh with GTX 650 card. the speedup is only 2 compared with one cpu core. I think the speed is too slow. Need i to improve the card to obtain futher improvement.

Could you please provide me some suggestions.
Regards

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
void Temperature::SolveGPU()
{

Mesh* RefMesh=VarBox->aMesh;
int nRow=RefMesh->CellsNumber;

std::vector< std::map< unsigned int, double> > cpumatrix(nRow);
std::vector<double> temp(nRow);

 for(int i=0;i<nRow;i++){
      int row1=RefMesh->CsrRow[i];
      int row2=RefMesh->CsrRow[i+1];
      for (int jj=row1; jj<row2; jj++)
        cpumatrix[i][RefMesh->CsrColumn[jj]]=A[jj];     
}

viennacl::compressed_matrix<double> vclmatrix(nRow,nRow);
viennacl::vector<double> x(nRow);
viennacl::vector<double> b(nRow);

fast_copy(Source.begin(), Source.end(), b.begin());
fast_copy(VarBox->T->Field.begin(), VarBox->T->Field.end(), x.begin());

copy(cpumatrix, vclmatrix);

viennacl::linalg::ilu0_precond< viennacl::compressed_matrix<double> > vcl_ilu0(vclmatrix, viennacl::linalg::ilu0_tag());
viennacl::linalg::jacobi_precond< viennacl::compressed_matrix<double> > vcl_jacobi(vclmatrix, viennacl::linalg::jacobi_tag()); 
viennacl::linalg::chow_patel_ilu_precond< viennacl::compressed_matrix<double> >ilu(vclmatrix,viennacl::linalg::chow_patel_tag());

viennacl::linalg::bicgstab_tag  tag(1e-10, 50);
viennacl::linalg::bicgstab_solver<viennacl::vector<double>> Solver(tag);
Solver.set_initial_guess(x);

     x = Solver(vclmatrix, b);
    std::cout <<std::endl<< "No. of iters: " << tag.iters() << std::endl;
    std::cout << std::endl<<"Est. error: " << tag.error() << std::endl;

fast_copy(x.begin(), x.end(), VarBox->T->Field.begin());

}

[Karl Rupp]

Hi Ding,

pass the solver to viennacl::linalg::solve(), i.e.

 x = viennacl::linalg::solve(vclmatrix, b, Solver);

See here for an example:
https://github.com/viennacl/viennacl-dev/blob/master/examples/tutorial/iterative.cpp#L198

I'm surprised that your code line x = Solver(vclmatrix,b) even compiled...

Best regards,
Karli

[p ding]

Dear Karli:
It compiled and worked . I follow the "CG" section in onlin tutorial .