[petsc-users] confusion on the use of fieldsplit

[Umut Tabak]

Dear all,

I am trying to use PETSc to solve linear systems where the operator 
matrices are composed of blocks. But I am having hard time to set up the 
PCFieldSplit, and a bit lost in the documentation. I sucessfully created 
the matrix represented as

A
=
A11 A12
A21 A22

with

MatCreateNest(PETSC_COMM_WORLD,nr,NULL,nc,NULL,sub_matrices,&blockA);

but I could not understand really the following steps on how to 
associate a KSP object with Field split properties to use different 
conditioners on different blocks? In the mean time, continue on reading. 
If you can outline the basic steps on how to construct this scheme and 
submit analysis with basic command line options, that would of great help.

By the way, is not possible to output blockA that is assembled above on 
the standard output?

Best regards,
Umut