On Fri, Sep 11, 2015 at 8:15 AM, Gideon Simpson <[email protected]> wrote:
> Ok, so here’s some behavior I don’t understand. I am working with a > DMComposite structure, and I do the following, > > SNESComputeFunction(snes,U_refine,r); > SNESGetDM(snes, &dm_refine); > > DMCompositeGetLocalVectors(dm_refine, &rp, &rQ); > DMCompositeScatter(dm_refine, r, rp, rQ); > > VecNorm(r, NORM_2, &r_norm); > VecNorm(rp, NORM_2, &rp_norm); > VecNorm(rQ, NORM_2, &rQ_norm); > > VecGetSize(r,&r_size); > VecGetSize(rp, &rp_size); > VecGetSize(rQ, &rQ_size); > > DMCompositeRestoreLocalVectors(dm_refine, &rp, &rQ); > VecDestroy(&r); > > PetscPrintf(PETSC_COMM_WORLD," ||r|| = %g, %i > entries\n",r_norm,r_size); > PetscPrintf(PETSC_COMM_WORLD," ||rp|| = %g, %i > entries\n",rp_norm,rp_size); > PetscPrintf(PETSC_COMM_WORLD," ||rQ|| = %g, %i > entries\n",rQ_norm,rQ_size); > > and my output is: > > ||r|| = 225.31, 7999 entries > ||rp|| = 140.021, 3 entries > ||rQ|| = 176.56, 8004 entries > > > The arithmetic, is off, no? > I think you want Global vectors for this, not Local vectors. Matt > -gideon > > On Sep 10, 2015, at 5:28 PM, Barry Smith <[email protected]> wrote: > > > SNESGetDM() this will return not the original DM you set but the refined > one. > > On Sep 10, 2015, at 3:47 PM, Gideon Simpson <[email protected]> > wrote: > > I’m using a DMCompsosite along with grid sequencing and here’s what I’m > trying to accomplish. After running the SNES solve, I’d like to evaluate > the residual on the refined grid, on each piece of the DMComposite. How do > I get a DM for the refined grid which I can then use with > DMCompositeGetLocalVectors in order to get each piece of the problem? Or > is there a better way? > > -gideon > > > > -- 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
