[petsc-users] nonzero prescribed boundary condition

Tue May 10 22:05:46 CDT 2011

   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>