Dear every dealii user,
Wish you good day!
I am a beginner to dealii. The version that I am using is 9.3.0.
I have caught with a problem when I am solving my FEM problems. Could anyone please help me with it?
I am intended to get all active cells` center point values, so I followed the tutorials and use the following coding.
//eg.
size_t cellCount = 0; //keep the cell`s count；
for (auto& cell : triangulation.active_cell_iterators())
{
//### get the cell`s center point solution：
double adata = dealii::VectorTools::point_value(dof_handler, solution, cell->center());

//### put the solution to a "VectorXd"：
phantVValues(vindex) = adata;

//### next cell：
++cellCount;
}
//END
The problem is that when my active cell`s amount is large, this coding is in vastly slow calculation speed. I find another dealii method to solve the problem,
which is as follows. However, it is also very 'expensive' for very large amount of cells.

//additional.
//### define a FEFieldFunction object 'solution_function',
dealii::Functions::FEFieldFunction<3, dealii::DoFHandler<3>, dealii::Vector<double>>
solution_function(dof_handler, solution);

size_t cellCount = 0; //keep the cell`s count；
for (const auto& cell : dof_handler.active_cell_iterators())
{
//### cell`s center axis：
dealii::Point<3> cCell = cell->center();

//### set this cell as active cell：
solution_function.set_active_cell(cell);

//### get the cell`s center point solution：
double adata = solution_function.value(cCell);

//### put the solution to a "VectorXd"：
phantVValues(vindex) = adata;

//### next cell：
++cell_Count;
}

//END

Are there any convenient and immediate methods in dealii version9.3.0 to get every cell center value?
I would be very appreciated if you can give me some suggestions.
Looking forward to your reply. Best wishes to you!

--

Yours，
sincerely.