Thank you! 在2022年10月28日星期五 UTC+8 22:50:37<Wolfgang Bangerth> 写道：
> On 10/28/22 00:50, 'yy.wayne' via deal.II User Group wrote: > > I have a question that if ghost_indices should be past to a vector's > reinit? > > In step-40 and line 89 of this test > > < > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fdealii%2Fdealii%2Fblob%2Fmaster%2Ftests%2Fmpi%2Fsolution_transfer_04.cc%23%3A~%3Atext%3Dsolution.reinit(locally_owned_dofs%2C%2520MPI_COMM_WORLD)%3B&data=05%7C01%7CWolfgang.Bangerth%40colostate.edu%7C7703891c22db47014d6308dab8b0c6be%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C638025366645029265%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=Q%2FZxqQEdJR%2FeoBSz8SNn0LAocgqvLtSV6tAmkUeeCeA%3D&reserved=0>, > > > > system_rhs and solution are reinit with reinit(local_dofs, > mpi_communicator) > > only. But in line 95 of that test > > < > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fdealii%2Fdealii%2Fblob%2Fmaster%2Ftests%2Fmpi%2Fsolution_transfer_04.cc%23%3A~%3Atext%3Dold_solution.reinit(locally_owned_dofs%2C&data=05%7C01%7CWolfgang.Bangerth%40colostate.edu%7C7703891c22db47014d6308dab8b0c6be%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C638025366645029265%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=YI0OrnoL5OxFwMaqTC7lxVpwgqL%2BS3dbkNDMPfI%2FmUo%3D&reserved=0>, > > > > we need ghost_indices as argument. That's same for one of my code, where > I > > found a bug because I didn't use locally_relevant_dofs when reinit a > > system_rhs. To reduce mistakes, should vectors always be reinit with > > ghost_indices then ? > > No. The question is whether you need ghost elements in the vector or not, > and > that is typically a question on whether you need to *read* individual > entries. > When you build the right hand side and when you call a solver to compute > the > solution vector, we use "completely distributed vectors" that do not have > ghost elements. When you want to output the solution graphically, however, > you > need to be able to read individual vector elements also for ghost entries, > and > so then you need the locally relevant dofs. Vectors with ghost elements > are > read-only. > > Best > W. > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > www: http://www.math.colostate.edu/~bangerth/ > > -- 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/7d28042c-c028-43f9-9768-f365c19da1f9n%40googlegroups.com.
