[petsc-users] Projection preconditioner as PCMG

[Abdul Hanan Sheikh]

Dear, 

To my earlier querry: 


What if I want to approximate my all coarse matrices with any Krylov iteration ?
reply: 

The methods on each 
level are independent, you can set them with -mg_coarse_ksp_type gmres 
-mg_levels_1_ksp_type cg -mg_levels_1_ksp_max_it 100 
-mg_levels_2_ksp_type minres ... 

 
This command line option changes the ksp_type on both ksp_pre and ksp_post (pre and post smoothing) . 
Where as I need to fix the ksp_post_type as RICHARDSON to get my Prec = C + I - AC ; 

If adapt pre_smoother as follows : 

ierr = MGGetSmootherDown(pcmg,lev,&ksp_pre); CHKERRQ(ierr); 
ierr = KSPSetType(ksp_pre, KSPGMRES);CHKERRQ(ierr);

Does ONLY setting pre_smoother as GMRES means that GMRES iterates on coarse matrix at level = lev ? 

Thanks in advance. 
Abdul. 
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