[petsc-users] How to solve the pressure possion equations with four neuman bc

[丁老师]

Dear professor:
     In the ksp example ex50.c, i do not understand the meaning of 
KSPSolve(ksp,NULL,NULL);
     nMatNullSpaceCreate(PETSC_COMM_WORLD,PETSC_TRUE,0,0,&nullspace);  
       What is the meaning of NULL in the kspsolve. and two "0" in the MatNullSpaceCreate.
Regards



 




At 2016-09-24 00:25:09, "Jed Brown" <jed at jedbrown.org> wrote:
>"Kong, Fande" <fande.kong at inl.gov> writes:
>
>> Any references on this topic except the users manual?  I am interested in
>> mathematics theory on this topic.
>
>These are relevant. I've only skimmed them briefly, but they might
>suggest ways to improve PETSc's handling of singular systems.  The
>technique is ancient.
>
>https://doi.org/10.1137/S0895479803437803
>
>https://doi.org/10.1007/s10543-009-0247-7
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