On Sat, Apr 11, 2015 at 7:03 PM, TAY wee-beng <[email protected]> wrote:
> Hi, > > I'm using DMDA. The LHS of the poisson eqn is fixed, only the RHS changes. > > I thought I can't find ex29.c in the current ver of PETSc, so I thought > it's no longer valid. Do I always have to get the jacobian as in ex29 to > solve the Poisson eqn? > It is there: https://bitbucket.org/petsc/petsc/src/0dbc604a2409e3ecaa129deb24062cf2be4d41a7/src/ksp/ksp/examples/tutorials/ex29.c?at=master > What about a good ex. using KSPBCGS to solve my momentum eqn with DMDA? > All examples are independent of the precise Krylov method. You can use that anywhere: cd src/snes/examples/tutorials make ex5 ./ex5 -ksp_type bcgs Thanks, Matt > Thank you. > > Yours sincerely, > > TAY wee-beng > > On 4/11/2015 6:43 AM, Barry Smith wrote: > >> Are you using DMDA or DMPLEX or some other DM? Does the Poisson >> equation change (variable coefficient) or is it a constant coefficient with >> the same values for all solves? ex29.c could still possibly serve as a >> model for the Poisson subproblem, why do you say it is no longer valid? >> >> Barry >> >> >> On Apr 8, 2015, at 10:18 PM, TAY wee-beng <[email protected]> wrote: >>> >>> Hi, >>> >>> I was following example ex29 in the past to write the code to solve my >>> Poisson eqn using DM. Now it seems that ex29 is no longer valid. Which >>> example should I follow now? >>> >>> Also, I am using KSPBCGS to solve my momentum eqn in the past. Do I need >>> to change much if I'm now using DM? If so, what is a good example? >>> >>> -- >>> Thank you >>> >>> Yours sincerely, >>> >>> TAY wee-beng >>> >>> > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
