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

[Barry Smith]

  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> 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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