Hello, I'm reading ex19.c from examples under directory snes. The version I'm 
using is 3.3. In the code, a user defined function NonlinearGS is implemented, 
and is registered thru the command
ierr = SNESSetGS(snes, NonlinearGS, (void*)&user);CHKERRQ(ierr);

I'm wondering if this only serves as a preconditioner? Because I read from the 
output that the default ksp solver is gmres. I'm also wondering what shall I do 
if I want to make the user defined NonlinearGS the actual solver instead of the 
preconditioner?

>From the discussion a few days ago, I knew that by specifying option -ksp_type 
>gmres or -ksp_type bcgs, you use gmres or bcgs as your solvers, where then can 
>I find a database for the ksp solvers?

Best,
Hui

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