[petsc-users] PC FieldSplit - How to Count the Iterations

Sonia Pozzi sonia.pozzi at usi.ch
Wed Mar 14 09:21:49 CDT 2018

Dear Barry,

thank you for the answer. That helped a lot. Just a second curiosity. 
I’m setting A00 to be solved with preonly+lu. I obtain the following
ksp_0  KSPGetTotalIterations: 26
ksp_1  KSPGetTotalIterations: 22
Residual ksp_0: 0 Reason ksp_0: 4
Solution ksp_0 :  Convergence in 1 iterations.
Residual ksp_1: 5.23074e-14 Reason ksp_1: 2
Solution ksp_1 :  Convergence in 11 iterations.
Initial system linear residual:  9.904804e-09 

To me is clear that kps_0 iterations number is equal to 22*1+2*2. 
But why is the iterations number for the schur complement multiplied by two?
I’m giving the mass matrix as a preconditioner for the schur complement.


Ph.D. Student
Group of Prof. Rolf Krause
Institute of Computational Science
Università della Svizzera italiana
Center for Computation Medicine in Cardiology
Via Giuseppe Buffi, 13
CH-6900 Lugano

Email: pozzis at usi.ch <mailto:pozzis at usi.ch> 
Phone: +41 58 666 4972

> On 14 Mar 2018, at 14:52, Smith, Barry F. <bsmith at mcs.anl.gov> wrote:
> KSPGetIterationNumber

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