[petsc-users] About the complex version of gmres.

[Barry Smith]

   I used src/ksp/ksp/tutorials/ex10.c and saved the A and b into a PETSc binary file from Matlab with PetscBinaryWrite() in PETSC_DIR/share/petsc/matlab


> On Jun 7, 2024, at 10:53 PM, neil liu <liufield at gmail.com> wrote:
> 
> Thanks  a  lot for your explanation. 
> Could you please share your petsc code to test this ?
> 
> Thanks,
> 
> Xiaodong 
> 
> On Fri, Jun 7, 2024 at 10:12 PM Barry Smith <bsmith at petsc.dev <mailto:bsmith at petsc.dev>> wrote:
>> 
>>   If I run with -pc_type lu it solves the system
>> 
>>   If I run with the default (ILU) -ksp_monitor_true_residual -ksp_converged_reason it does not converge. In fact, it makes no real progress to the solution.
>> 
>>   It is always important to use KSPGetConvergedReason() or -ksp_converged_reason or -ksp_error_if_not_converged to check that the solver has actually converged.
>> 
>>   If I run with -ksp_gmres_restart 100 it converges in 75 iterations.
>> 
>>  Barry
>> 
>> 
>> 
>> 
>>> On Jun 7, 2024, at 8:03 PM, neil liu <liufield at gmail.com <mailto:liufield at gmail.com>> wrote:
>>> 
>>> This Message Is From an External Sender
>>> This message came from outside your organization.
>>> Dear Petsc developers, 
>>> 
>>> I am using Petsc to solve a complex system ,AX=B.
>>> 
>>> A is complex and B is real. 
>>> 
>>> And the petsc was configured with 
>>> Configure options --download-mpich --download-fblaslapack=1 --with-cc=gcc --with-cxx=g++ --with-fc=gfortran --download-triangle --with-scalar-type=complex
>>> 
>>> A and B were also imported to matlab and the same system was solved.
>>> The direct and iterative solver in matlab give the same result, which are quite different from the result from Petsc. 
>>> A and B are attached. x from petsc is also attached. I am using only one processor. 
>>> 
>>> It is weird. 
>>> 
>>> Thanks a lot.
>>> 
>>> Xiaodong 
>>> <A.m><xPetsc.m><B.m>
>> 

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