Ok, the linear solver looks like it is working ok. The likely problem is that Jacobian does not match the function evaluation.
Run the same thing but with the additional option -snes_mf_operator Then run with -snes_type test (instead of -snes_mf_operator). Barry On May 10, 2011, at 8:14 PM, Tian(ICT) wrote: > Dear Barry, here is the output using -pc_type lu -ksp_monitor_true_residual > -snes_monitor -ksp_monitor > the attached is the same and for clear reference. Thanks again for helps. > > atol=1e-050, rtol=1e-008, stol=1e-008, maxit=50, maxf=10000 > 0 SNES Function norm 7.071067811865e-002 > 0 KSP Residual norm 9.965778978387e-002 > 0 KSP preconditioned resid norm 9.965778978387e-002 true resid norm > 7.071067811865e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 6.823187455811e-017 > 1 KSP preconditioned resid norm 6.823187455811e-017 true resid norm > 8.847298885656e-011 ||Ae||/||Ax|| 1.251197007446e-009 > 1 SNES Function norm 6.401926523423e-002 > 0 KSP Residual norm 8.969200212486e-002 > 0 KSP preconditioned resid norm 8.969200212486e-002 true resid norm > 6.401926523423e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 1.106757475780e-016 > 1 KSP preconditioned resid norm 1.106757475780e-016 true resid norm > 6.211830067439e-011 ||Ae||/||Ax|| 9.703063671087e-010 > 2 SNES Function norm 5.849992149767e-002 > 0 KSP Residual norm 8.072279488157e-002 > 0 KSP preconditioned resid norm 8.072279488157e-002 true resid norm > 5.849992149767e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 1.268750073799e-017 > 1 KSP preconditioned resid norm 1.268750073799e-017 true resid norm > 3.802431036387e-011 ||Ae||/||Ax|| 6.499890835816e-010 > 3 SNES Function norm 5.376618503592e-002 > 0 KSP Residual norm 7.265050969883e-002 > 0 KSP preconditioned resid norm 7.265050969883e-002 true resid norm > 5.376618503592e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 2.677655733356e-017 > 1 KSP preconditioned resid norm 2.677655733356e-017 true resid norm > 8.120397788686e-011 ||Ae||/||Ax|| 1.510316899602e-009 > 4 SNES Function norm 4.956894354459e-002 > 0 KSP Residual norm 6.538545411661e-002 > 0 KSP preconditioned resid norm 6.538545411661e-002 true resid norm > 4.956894354459e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 9.557004153175e-017 > 1 KSP preconditioned resid norm 9.557004153175e-017 true resid norm > 2.944250802029e-011 ||Ae||/||Ax|| 5.939708598754e-010 > 5 SNES Function norm 4.575418613137e-002 > 0 KSP Residual norm 5.884690496914e-002 > 0 KSP preconditioned resid norm 5.884690496914e-002 true resid norm > 4.575418613137e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 5.470969262115e-017 > 1 KSP preconditioned resid norm 5.470969262115e-017 true resid norm > 3.659003166095e-011 ||Ae||/||Ax|| 7.997089393284e-010 > 6 SNES Function norm 4.223022245585e-002 > 0 KSP Residual norm 5.296221144636e-002 > 0 KSP preconditioned resid norm 5.296221144636e-002 true resid norm > 4.223022245585e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 8.255198782390e-017 > 1 KSP preconditioned resid norm 8.255198782390e-017 true resid norm > 1.955545658933e-011 ||Ae||/||Ax|| 4.630678090739e-010 > 7 SNES Function norm 3.894430065910e-002 > 0 KSP Residual norm 4.766598785088e-002 > 0 KSP preconditioned resid norm 4.766598785088e-002 true resid norm > 3.894430065910e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 3.322615478395e-017 > 1 KSP preconditioned resid norm 3.322615478395e-017 true resid norm > 3.485328148673e-011 ||Ae||/||Ax|| 8.949520442496e-010 > 8 SNES Function norm 3.586683371135e-002 > 0 KSP Residual norm 4.289938708067e-002 > 0 KSP preconditioned resid norm 4.289938708067e-002 true resid norm > 3.586683371135e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 6.181358328498e-017 > 1 KSP preconditioned resid norm 6.181358328498e-017 true resid norm > 3.246902818086e-011 ||Ae||/||Ax|| 9.052660862724e-010 > 9 SNES Function norm 3.298130202025e-002 > 0 KSP Residual norm 3.860944676473e-002 > 0 KSP preconditioned resid norm 3.860944676473e-002 true resid norm > 3.298130202025e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 4.635174776374e-017 > 1 KSP preconditioned resid norm 4.635174776374e-017 true resid norm > 1.497516842272e-011 ||Ae||/||Ax|| 4.540502498513e-010 > 10 SNES Function norm 3.027806208930e-002 > 0 KSP Residual norm 3.474850078591e-002 > 0 KSP preconditioned resid norm 3.474850078591e-002 true resid norm > 3.027806208930e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 2.389914053685e-017 > 1 KSP preconditioned resid norm 2.389914053685e-017 true resid norm > 6.007440888596e-011 ||Ae||/||Ax|| 1.984090286517e-009 > 11 SNES Function norm 2.749422924729e-002 > 0 KSP Residual norm 3.081350823297e-002 > 0 KSP preconditioned resid norm 3.081350823297e-002 true resid norm > 2.749422924729e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 2.640567497647e-017 > 1 KSP preconditioned resid norm 2.640567497647e-017 true resid norm > 1.281638295853e-011 ||Ae||/||Ax|| 4.661481085089e-010 > 12 SNES Function norm 2.437488247885e-002 > 0 KSP Residual norm 2.633007441879e-002 > 0 KSP preconditioned resid norm 2.633007441879e-002 true resid norm > 2.437488247885e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 2.772331460094e-017 > 1 KSP preconditioned resid norm 2.772331460094e-017 true resid norm > 1.918212496143e-011 ||Ae||/||Ax|| 7.869627670236e-010 > 13 SNES Function norm 2.079664278637e-002 > 0 KSP Residual norm 2.104738289397e-002 > 0 KSP preconditioned resid norm 2.104738289397e-002 true resid norm > 2.079664278637e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 1.650632708670e-017 > 1 KSP preconditioned resid norm 1.650632708670e-017 true resid norm > 2.316371967362e-011 ||Ae||/||Ax|| 1.113820144509e-009 > 14 SNES Function norm 1.657344626858e-002 > 0 KSP Residual norm 1.454141853505e-002 > 0 KSP preconditioned resid norm 1.454141853505e-002 true resid norm > 1.657344626858e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 1.129401160070e-017 > 1 KSP preconditioned resid norm 1.129401160070e-017 true resid norm > 7.885499327559e-012 ||Ae||/||Ax|| 4.757911661686e-010 > 15 SNES Function norm 1.484243752612e-002 > 0 KSP Residual norm 5.241948491751e-009 > 0 KSP preconditioned resid norm 5.241948491751e-009 true resid norm > 1.484243752612e-002 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 2.729506849025e-024 > 1 KSP preconditioned resid norm 2.729506849025e-024 true resid norm > 6.386677851085e-018 ||Ae||/||Ax|| 4.302984492839e-016 > 16 SNES Function norm 2.828002157497e-008 > 0 KSP Residual norm 6.042518362322e-015 > 0 KSP preconditioned resid norm 6.042518362322e-015 true resid norm > 2.828002157497e-008 ||Ae||/||Ax|| 1.000000000000e+000 > 1 KSP Residual norm 6.272441346127e-030 > 1 KSP preconditioned resid norm 6.272441346127e-030 true resid norm > 1.112857698032e-023 ||Ae||/||Ax|| 3.935137372797e-016 > 17 SNES Function norm 2.960967020289e-008 > STEP 0 (Newton iterations: 17) > > diverged reason: -6 > > > ----- Original Message ----- From: "Barry Smith" <bsmith at mcs.anl.gov> > To: "PETSc users list" <petsc-users at mcs.anl.gov> > Sent: Wednesday, May 11, 2011 2:54 AM > Subject: Re: [petsc-users] nonzero prescribed boundary condition > > > > Use -pc_type lu -ksp_monitor_true_residual -snes_monitor -ksp_monitor and > send the outputs > > > Barry > > On May 9, 2011, at 10:43 PM, Tian(ICT) wrote: > >> by the way, the increment size is like that >> for a 100 lengh model, the increment is set to 0.05, >> the engineering strain is around 5%% per load step. >> This is already too small increment size for a large deformation analysis. >> a 0.5 increment size leads to both linear search and trust region failed. >> linear search failed for 0.05 while trust region converges with 17 Newton >> iterations each load step. >> Rong >> >> ----- Original Message ----- From: "Tian(ICT)" <rongtian at ncic.ac.cn> >> To: "PETSc users list" <petsc-users at mcs.anl.gov> >> Sent: Tuesday, May 10, 2011 11:37 AM >> Subject: Re: [petsc-users] nonzero prescribed boundary condition >> >> >>> First, thanks again, the issue was gone. >>> >>> I just followed up with some test results. >>> I have tested SNES using one finite element for a geometric large >>> deformation problem. >>> Those are just the very early test results so they may be not telling what >>> happened exactly. >>> For the displacement controlled load, I found that convergence is much >>> slower than that of force loading. >>> Even worse, linear search is so sensitive to the displacement increment and >>> diverged no matter what the increment size was used (too small incremnt >>> also led to diverged soloution (-6 reason), trust region works well in the >>> sense of not sensitive to the displacement increment, but during each load >>> step, it requires around ten to several tens of Newton interations whereas >>> for the force loading case and the almost same amount of deformation, this >>> is normally 3. This is against my expectation. Any hint? >>> >>> Rong >>> >>> ----- Original Message ----- From: "Barry Smith" <bsmith at mcs.anl.gov> >>> To: "PETSc users list" <petsc-users at mcs.anl.gov> >>> Sent: Tuesday, May 10, 2011 10:22 AM >>> Subject: Re: [petsc-users] nonzero prescribed boundary condition >>> >>> >>> >>> On May 9, 2011, at 9:15 PM, Tian(ICT) wrote: >>> >>>> Dear Barry, Thanks a lot for quick answering. >>>> I checked the development documents and found the new version of >>>> MatZeroRows() does support the nonzero prescribed boundary conditions. >>>> >>>> I followed up with more details. >>>> I am using Petasc 2.3.3. to solve a nonlinear problem, e.g. using SNES >>>> solvers. >>>> I used a displacement-controlled load (as this type of loading works well >>>> for all cases). >>>> This is the reason the nonzero prescribed boundary came up. >>>> >>>> In FormJacobian, I modified Jacobian and residual to satisfy the nonzero >>>> prescribed boundary. >>>> In FormFunction, I modified the solution to the known solution(this should >>>> not be necessary as the modified Jacobian and rhs should give the >>>> prescribed solution also) >>> >>> You should not do it this way. See below. >>>> >>>> Now I found another issue, no matter if I prescried the solution or not in >>>> FormFunction, >>>> SNES solver always call FormFunction and never call FormJacobian. >>> >>> The only reason it would not call FormJacobian is if decided that the >>> residual norm was small enough before any Newton steps; for example if the >>> FormFunction() computed exactly the zero function initially. When you run >>> with -snes_monitor -ksp_monitor what does it print for residual norms. >>> >>>> Of course the solver finally diverged or converged to a zero solution. >>>> >>>> So my quick follow up question is How a displacement-controled load is >>>> done corrently in Petsc 2.3.3? >>> >>> To do it in 2.3.3 simply have for those components of F() the formula F_i = >>> x_i - givenvalue_i and in your Jacobian just use MatZeroRows() for those >>> rows >>> >>> We strongly urge you to upgrade to the latest PETSc before doing anything >>> further. >>> >>> >>> Barry >>> >>>> >>>> Rong >>>> >>>> ----- Original Message ----- From: "Barry Smith" <bsmith at mcs.anl.gov> >>>> To: "PETSc users list" <petsc-users at mcs.anl.gov> >>>> Sent: Tuesday, May 10, 2011 9:31 AM >>>> Subject: Re: [petsc-users] nonzero prescribed boundary condition >>>> >>>> >>>> >>>> In petsc-dev http://www.mcs.anl.gov/petsc/petsc-as/developers/index.html >>>> we have modified the calling sequence for MatZeroRows() so that it can >>>> automatically adjust the appropriate right hand side values for the zeroed >>>> rows to support zero or non-zero prescribed boundary conditions easily. >>>> >>>> Barry >>>> >>>> On May 9, 2011, at 8:18 PM, Tian(ICT) wrote: >>>> >>>>> Dear all, >>>>> >>>>> I got this question long ago and searched the prior posting but did not >>>>> find the solution. >>>>> The question is about nonzero prescribed boundary condition. >>>>> My understanding is that MatZeroRows() works only for zero prescribed >>>>> value, not non-zero value. >>>>> For the non-zero values, we have to remove the rows associated with the >>>>> boundary, but this >>>>> will lead to a zero dignal and accordingly the rows in r.h.s should also >>>>> be removed. >>>>> My question is that does MatZeroRows() also works for nonzero prescribed >>>>> boundary and if so how to do it simply? >>>>> >>>>> Rong >>>> >>>> >>> >>> >> > > <aa>
