I'll do some further test. Your advice on locating NaN error really helps me. Thank you Wolfgang :)
Best, Wayne 在2023年2月15日星期三 UTC+8 12:17:44<Wolfgang Bangerth> 写道： > On 2/14/23 19:04, 'yy.wayne' via deal.II User Group wrote: > > > > Yes the diagonal could be negative when k rises. Will Chebyshev > preconditioner > > smoother converge > > when there are negative entries? > > I have no idea :-) > > > > In my case k hasn't rise so large that diagonal entries is negative. The > > negative entries shows up only > > when compute_normal_flux constraints is applied. I think > > AffineConstraints::distribute_local_to_global > > < > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.dealii.org%2Fcurrent%2Fdoxygen%2Fdeal.II%2FclassAffineConstraints.html%23a373fbdacd8c486e675b8d2bff8943192%3A~%3Atext%3DThus%2C%2520if%2520a%2520degree%2Cin%2520the%2520global%2520matrix.&data=05%7C01%7CWolfgang.Bangerth%40colostate.edu%7Cd2ecd8f014fc4c51b63308db0ef8fd28%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C638120234786119642%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=c2TyCwiADwVWxKmtOEDrujHEkVC%2F8QPR5k7gIip3OoQ%3D&reserved=0 > > > > is the cause since in matrix-based assemble, this function add a > positive > > value on the constrained > > dofs while matrix-free does not. Therefore the diagonals are different > between > > matrix-free and matrix-based. > > That's possible. I don't know enough about the matrix-free framework to > tell > one way or the other, but maybe some of my colleagues here will know. > > Best > W. > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > 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 dealii+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/7c40c32c-5802-4911-9143-1971a158c81dn%40googlegroups.com.
