2012/8/29 Vikram Garg <[email protected]>:
> Hey Yuanwu,
> Can you tell us what kind of linear solver options you
> are using (the method, preconditioner options passed at runtime) ?
I used the default option. (I don't know what's the default?)
#EquationSystems
n_systems()=1
System #0, "homogenization_elastic_3D_plate"
Type "LinearImplicit"
Variables="u" "v" "w"
Finite Element Types="LAGRANGE" "LAGRANGE" "LAGRANGE"
Approximation Orders="FIRST" "FIRST" "FIRST"
n_dofs()=648
n_local_dofs()=648
n_constrained_dofs()=198
n_local_constrained_dofs()=198
n_vectors()=13
n_matrices()=1
DofMap Sparsity
Average On-Processor Bandwidth <= 84
Average Off-Processor Bandwidth <= 0
Maximum On-Processor Bandwidth <= 144
Maximum Off-Processor Bandwidth <= 0
DofMap Constraints
Number of DoF Constraints = 198
Average DoF Constraint Length= 1
> If you
> are using the same stiffness matrix (K) and just changing the rhs (F),
That's just what I'm doing.
> then
> you might actually be better of just using the LU preconditioner for one
> load and reusing it for the others.
How to set it in my code? Can you give me a simple example?
Thanks for your answer!
>
> Thanks.
>
> On Tue, Aug 28, 2012 at 8:45 PM, 蔡园武 <[email protected]> wrote:
>>
>> Hi, guys,
>> I have a LinearImplicitSystem, solved with a sequential of different
>> force vectors (rhs).
>> Actually I defined different 'Fe' assemble function using a 'loadcase'
>> indicator. In main function, I set the 'loadcase' value, call
>> system.solve(), then es.reinit(), set a new 'loadcase' value, and
>> solve() again.
>> But I found that for some 'loadcase', the solver converged badly, like:
>>
>> loadcase1: Linear solver converged at step: 10736, final residual:
>> 2.00331e-21
>> loadcase2: Linear solver converged at step: 8549, final residual:
>> 2.10685e-21
>> loadcase3: Linear solver converged at step: 8, final residual: 1.38269e-07
>> loadcase4: Linear solver converged at step: 0, final residual: 0.463112
>> loadcase5: Linear solver converged at step: 0, final residual: 0.463112
>> loadcase6: Linear solver converged at step: 0, final residual: 0.463112
>>
>> In loadcase3, Linear solver converged at step 8, final resudual is not
>> small enough. It's very strange that the loadcases after this didn't
>> run? (converged at step 0?) The results are wrong and unbelievable.
>> But if I solve loadcase3 after all the other loadcases, then loadcase
>> 4,5,6 will be all right. Don't know why?
>>
>> Can I mannually control the final resudual tolerance? I did set a
>> parameter in es:
>> es.parameters.set<unsigned int> ("linear solver maximum
>> iterations") = 20000;
>> es.parameters.set<Real> ("linear solver tolerance") = TOLERANCE;
>>
>> Thanks for your help！
>> --
>> Cai Yuanwu 蔡园武
>> Dept. of Engineering Mechanics,
>> Dalian University of Technology,
>> Dalian 116024, China
>>
>>
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>
>
>
>
> --
> Vikram Garg
> PhD Candidate
> Institute for Computational and Engineering Sciences
> The University of Texas at Austin
>
> http://users.ices.utexas.edu/~vikram/
> http://www.runforindia.org/runners/vikramg
>
--
Cai Yuanwu 蔡园武
Dept. of Engineering Mechanics,
Dalian University of Technology,
Dalian 116024, China
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Exclusive live event will cover all the ways today's security and
threat landscape has changed and how IT managers can respond. Discussions
will include endpoint security, mobile security and the latest in malware
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
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