Thank you Daniel.
在2022年9月26日星期一 UTC+8 20:42:54<d.arnd...@gmail.com> 写道：
> cell_worker and copier are lambda functions. You can think of them as
> in-place structs with a call operator (operator()) with the specified
> signature. We define a new cell_worker object because the place we are
> passing it into expects the object to have a call operator that does what
> this->cell_worker implements.
>
> Best,
> Daniel
>
> On Sun, Sep 25, 2022 at 11:02 PM 'yy.wayne' via deal.II User Group <
> dea...@googlegroups.com> wrote:
>
>> In step16 function assemble_system() and assemble_multigrid(), there are
>> 2 variables/functions defined as:
>> auto cell_worker =
>> [&](const typename DoFHandler<dim>::active_cell_iterator &cell,
>> ScratchData<dim> & scratch_data,
>> CopyData & copy_data)
>> { this->cell_worker(cell, scratch_data, copy_data); };
>> auto copier =
>> [&](const CopyData &cd)
>> { this->constraints.distribute_local_to_global(cd.cell_matrix,
>>
>> cd.cell_rhs,
>>
>> cd.local_dof_indices,
>>
>> system_matrix, system_rhs); };
>> I'm not expert in C++ and these codes seem confusing to me. Are
>> *cell_worker* and *copier* defined here variables or functions? And why
>> we define a new cell_worker here (is it because we cannot directly pass
>> this->cell_worker to MeshWorker::mesh_loop) ? Sorry it might be silly.
>> Should I know the terminology for this "technique" I can google myself.
>> Thank you.
>>
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