On Thu, Aug 9, 2012 at 9:21 AM, Sanjay Govindjee <s_g at berkeley.edu> wrote:
> Colin, > I you block the equations in FEAP, then the restrained BCs are > 'included' in assembled PETSc matrix (these dofs have rows that are zero > modulo a value of unity on the diagonal and the restrained value on the > right-hand side). > However, this is not necessary with the DM interface. Matt > -sg > > On 8/9/12 8:41 AM, Colin McAuliffe wrote: > >> From what I can gather from the petsc-dev source it looks like the >> commands in 4) will then generate the splits using strided blocks. The >> problem with that is the fortran code I am using (FEAP) uses petsc to >> assemble and solve the linear problem within its own nonlinear and time >> stepping schemes. The linear problem that petsc solves already has boundary >> conditions applied to it so petsc only sees the active (unrestrained) >> equations. So then in general fields can't be extracted from the active >> equations using strided blocks and I am stuck with generating the index >> sets defining the splits on my own. Will it still be possible to make use >> of the new DM functions in this case? >> >> FEAP website: >> http://www.ce.berkeley.edu/**projects/feap/<http://www.ce.berkeley.edu/projects/feap/> >> >> Colin >> >> >> Quoting Matthew Knepley <knepley at gmail.com>: >> >> On Wed, Aug 8, 2012 at 10:51 PM, Matthew Knepley <knepley at gmail.com> >>> wrote: >>> >>> On Wed, Aug 8, 2012 at 10:23 PM, Colin McAuliffe <cjm2176 at columbia.edu >>>> >wrote: >>>> >>>> Thanks all, regarding use of DM in 3.3, is the procedure now to create >>>>> the fields with PCFieldSplitSetIS and then use >>>>> DMCreateFieldDecompositionDM >>>>> to create a new DM based from the new fields and the DM for the >>>>> original >>>>> problem? >>>>> >>>>> >>>> 1) Use petsc-dev >>>> >>>> 2) PCFieldSplitSetIS() is independent. This allows you to define splits >>>> however you want, but then recursive gets harder >>>> >>>> 3) In 3.3., it uses DMCreateFieldDecompositionDM() to split all fields >>>> apart at once >>>> >>>> 4) In petsc-dev, it uses DMCreateSubDM() which can split off any >>>> combination of fields, which from the command line is something like >>>> >>>> -pc_fieldsplit_0_fields 2,0 -pc_fieldsplit_1_fields 1,3 >>>> >>>> >>> I should have shown recursive: >>> >>> -fieldsplit_0_pc_type fieldsplit >>> >>> will split 2,0 into two blocks. >>> >>> Matt >>> >>> >>> Matt >>>> >>>> >>>> Colin >>>>> >>>>> -- >>>>> Colin McAuliffe >>>>> PhD Candidate >>>>> Columbia University >>>>> Department of Civil Engineering and Engineering Mechanics >>>>> >>>>> >>>> >>>> >>>> -- >>>> 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 >>>> >>>> >>> >>> >>> -- >>> 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 >>> >>> >> >> >> > -- > ------------------------------**----------------- > Sanjay Govindjee, PhD, PE > Professor of Civil Engineering > Vice Chair for Academic Affairs > > 779 Davis Hall > Structural Engineering, Mechanics and Materials > Department of Civil Engineering > University of California > Berkeley, CA 94720-1710 > > Voice: +1 510 642 6060 > FAX: +1 510 643 5264 > s_g at berkeley.edu > http://www.ce.berkeley.edu/~**sanjay <http://www.ce.berkeley.edu/~sanjay> > ------------------------------**----------------- > > -- 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/20120809/ded434c2/attachment.html>
