Barry, Jed pointed out the paper by Tang et al. That paper (Table 1 in page 348) contains a very comprehensive view of different ways to compose preconditioners with deflation. Even though the paper talks about only CG, but I guess the methods in general apply to various Krylov methods (I haven't ruled the details yet).
Jie ----- Original Message ----- From: "Barry Smith" <[email protected]> To: "For users of the development version of PETSc" <petsc-dev at mcs.anl.gov> Sent: Sunday, March 3, 2013 3:55:04 PM Subject: Re: [petsc-dev] Deflated Krylov solvers for PETSc The beauty of the composing precondition preconditioners approach is that if one has a good preconditioner for "part" of the solution space then all one needs is to find good preconditioners for the other "parts" of the solution space. One doesn't need to worry about finding a good preconditioner for the troublesome part of AM, one only needs a good preconditioner for the part of the solution space that M does not handle well. Is it different for deflation? Barry
