Timo, Great! I looked at Utilities::MPI::sum() and it might be exactly what I need.
Do I use it in this way? double global_quantity = 0; for locally_owned_cell quantity += local_cell_contribution Utilities::MPI::sum(global_quantity, mpi_communicator); Thanks so much for the quick reply! Weixiong 在 2017年5月4日星期四 UTC-7下午1:36:24，Timo Heister写道： > > Weixiong, > > this depends on what you want to compute exactly: > - There is VectorTools::compute_global_error() that does the MPI > reduction for you > - There are wrappers around MPI commands like Utilities::MPI::sum(), > max(), ... > - you can always use MPI directly > - If you have parallel vectors you can use things functions like norms > that will do the reduction > > On Thu, May 4, 2017 at 4:29 PM, Weixiong Zheng <zwxn...@gmail.com > <javascript:>> wrote: > > Hi > > > > I didn't find a related Q&A so I put this here: how do I estimate a > quantity > > by integrating the solution over the whole problem domain when using MPI > > > > I am developing a code using MPI, which is my first time involving it > based > > on the way presented in Step 42. If you could tell me a specific way or > some > > hint, either about deal.II or MPI, I would appreciate the help! > > > > Best, > > Weixiong > > > > -- > > The deal.II project is located at > https://urldefense.proofpoint.com/v2/url?u=http-3A__www.dealii.org_&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=W0qWfYmBuL0rBqxAOuDxuXZvXNSLmuWV7hHajZwJmFc&s=0jXBq985YhyM700CpHhtm_RSOfHoGSyfMMTpcheMluA&e= > > > For mailing list/forum options, see > > > https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_forum_dealii-3Fhl-3Den&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=W0qWfYmBuL0rBqxAOuDxuXZvXNSLmuWV7hHajZwJmFc&s=4Q28VjVeu_OgmcBoV_KqALvZBehRk4pCL5lct8bNu5A&e= > > > --- > > 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 dealii+un...@googlegroups.com <javascript:>. > > For more options, visit > https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_optout&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=W0qWfYmBuL0rBqxAOuDxuXZvXNSLmuWV7hHajZwJmFc&s=BAoWybnRq_9De34vw0UoKcEoldzNmDZOMVTjuXm6YHI&e= > > . > > > > -- > 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
