On Thu, May 17, 2012 at 2:43 PM, Zhenglun (Alan) Wei <zhenglun.wei at gmail.com > wrote:
> On 5/17/2012 1:11 PM, Matthew Knepley wrote: > > On Thu, May 17, 2012 at 1:47 PM, Zhenglun (Alan) Wei < > zhenglun.wei at gmail.com> wrote: > >> Dear All, >> I hope you're having a nice day. >> I was trying to solve the Poisson equation with >> /src/ksp/ksp/exmaples/tutorial/ex45.c; however, it always give me the same >> result. I recalled the PetscLogStages and resolved this problem. However, >> the process of reconstructing DM costs a lot of computational time. I >> wonder do I have to use PetscLogStages to solve this problem, since, I >> thought, this function is only needed for using DMMG. Or as long as DM >> twice in one program, then I need to call PetscLogStages. >> > > I cannot understand what you mean. PetscLog functions only affect > logging. > > Matt > > >> thanks, >> Alan >> > > > > -- > 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 > > Dear Dr. Knepley, > I'm sorry for confusing you. Here I attached a old version of > /src/ksp/ksp/examples/tutorials/ex50.c. By adopting its approach of > PetscLogStage, I can solve Poisson equation twice with two different RHS in > one program. However, as you may noticed, this method, in ex50.c, is used > for DMMG. What I understand is that the DMMG has a severe limitation so > that the PetscLogStage is needed in order to solve the equation twice with > two different RHS. I wonder if I have to use this approach for KSP? This > method requires a lot of time to KSPCreate and DMMGCreate3d/2d in order to > construct the DM. That's why I want to find an alternative way. > No, PetscLogStage has nothing to do with solving with different RHS. It is only there so you can separately time the solves. Matt > thanks, > Alan > -- 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120517/da4b7175/attachment.htm>
