That's great. Thank you. 在2023年1月4日星期三 UTC+8 03:32:48<Timo Heister> 写道：
> This is not documented well and the doxygen types shown are not very > helpful. In the end it boils down to the following: > *_mg_* functions return level or multigrid iterators that have an > accessor (that is inside the iterator) with the template argument > level_dof_access = true. The only difference, if I remember correctly, > is that get_active_or_mg_dof_indices() will return the result of > get_mg_dof_indices() instead of get_dof_indices(). So, if you use > level iterators, you can use get_active_or_mg_dof_indices() in your > assembly and it will automatically do the right thing. This means you > can use the same assembler for active and mg levels. > > See > https://www.dealii.org/developer/doxygen/deal.II/classDoFCellAccessor.html#a15ef35e919b1005dc6050f9bca96956d > > On Sun, Jan 1, 2023 at 8:45 AM 'yy.wayne' via deal.II User Group > <[email protected]> wrote: > > > > I'm a bit confused on the effect of cell_iterators (similar ones are > cell_iterators_on_level and dof_handler. begin()) and mg_cell_iterators. In > step16, begin_mg() is used when assembling multigrid, while in step56 we > use cell_iterators rather > > ZjQcmQRYFpfptBannerStart > > This Message Is From an External Sender > > Use caution when opening links or attachments if you do not recognize > the sender. > > > > ZjQcmQRYFpfptBannerEnd > > I'm a bit confused on the effect of cell_iterators (similar ones are > cell_iterators_on_level and dof_handler.begin()) and mg_cell_iterators. In > step16, begin_mg() is used when assembling multigrid, while in step56 we > use cell_iterators rather than mg_cell_iterators. I think they both loop > through all cells, active or not. In documentation the difference is > mg_cell_iterators "return an iterator in their level-cell form". May some > expert explain this a little further? > > > > -- > > The deal.II project is located at http://www.dealii.org/ > > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > > --- > > You received this message because you are subscribed to the Google > Groups "deal.II User Group" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected]. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/a52ed968-d0d3-4cf9-be1a-ccd96de3e5f4n%40googlegroups.com > . > > > > -- > Timo Heister > http://www.math.clemson.edu/~heister/ > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/3d61f1d9-4cb4-4b8a-b0b5-210a643b72dan%40googlegroups.com.
