Yeah, but doesn't it only work with the local vectors localX and localF? Miguel
On Fri, Sep 26, 2014 at 10:10 AM, Matthew Knepley <knep...@gmail.com> wrote: > On Fri, Sep 26, 2014 at 10:06 AM, Miguel Angel Salazar de Troya < > salazardetr...@gmail.com> wrote: > >> That means that if we call SNESSetFunction() we don't build the residual >> vector in parallel? In the pflow example ( >> http://www.mcs.anl.gov/petsc/petsc-as/petsc-current/src/snes/examples/tutorials/network/pflow/pf.c.html) >> the function FormFunction() (Input for SNESSetFunction() works with the >> local vectors. I don't understand this. >> > > FormFunction() in that link clearly takes in a global vector X and returns > a global vector F. Inside, it > converts them to local vectors. This is exactly what you would do for a > function given to SNESSetFunction(). > > Matt > > >> >> Thanks >> Miguel >> >> On Fri, Sep 26, 2014 at 9:34 AM, Matthew Knepley <knep...@gmail.com> >> wrote: >> >>> On Fri, Sep 26, 2014 at 9:31 AM, Miguel Angel Salazar de Troya < >>> salazardetr...@gmail.com> wrote: >>> >>>> Thanks. I had another question about the DM and SNES and TS. There are >>>> similar routines to assign the residual and jacobian evaluation to both >>>> objects. For the SNES case are: >>>> >>>> DMSNESSetFunctionLocal >>>> DMSNESSetJacobianLocal >>>> >>>> What are the differences of these with: >>>> >>>> SNESSetFunction >>>> SNESSetJacobian >>>> >>> >>> SNESSetFunction() expects the user to construct the entire parallel >>> residual vector. DMSNESSetFunctionLocal() >>> expects the user to construct the local pieces of the residual, and then >>> it automatically calls DMLocalToGlobal() >>> to assembly the full residual. It also converts the input from global >>> vectors to local vectors, and in the case of >>> DMDA multidimensional arrays. >>> >>> Thanks, >>> >>> Matt >>> >>> >>>> and when should we use each? With "Local", it is meant to evaluate the >>>> function/jacobian for the elements in the local processor? I could get the >>>> local edges in DMNetwork by calling DMNetworkGetEdgeRange? >>>> >>>> Miguel >>>> >>>> On Thu, Sep 25, 2014 at 5:17 PM, Matthew Knepley <knep...@gmail.com> >>>> wrote: >>>> >>>>> On Thu, Sep 25, 2014 at 5:15 PM, Miguel Angel Salazar de Troya < >>>>> salazardetr...@gmail.com> wrote: >>>>> >>>>>> > If you need a symmetric Jacobian, you can use the BC facility in >>>>>> > PetscSection, which eliminates the >>>>>> > variables completely. This is how the FEM examples, like ex12, work. >>>>>> >>>>>> Would that be with PetscSectionSetConstraintDof ? For that I will >>>>>> need the PetscSection, DofSection, within DMNetwork, how can I obtain >>>>>> it? I >>>>>> could cast it to DM_Network from the dm, networkdm, declared in the main >>>>>> program, maybe something like this: >>>>>> >>>>>> DM_Network *network = (DM_Network*) networkdm->data; >>>>>> >>>>>> Then I would loop over the vertices and call >>>>>> PetscSectionSetConstraintDof if it's a boundary node (by checking the >>>>>> corresponding component) >>>>>> >>>>>> I admit to not completely understanding DMNetwork. However, it >>>>> eventually builds a PetscSection for data layout, which >>>>> you could get from DMGetDefaultSection(). The right thing to do is >>>>> find where it builds the Section, and put in your BC >>>>> there, but that sounds like it would entail coding. >>>>> >>>>> Thanks, >>>>> >>>>> Matt >>>>> >>>>> >>>>>> Thanks for your responses. >>>>>> >>>>>> Miguel >>>>>> >>>>>> >>>>>> >>>>>> On Thu, Sep 25, 2014 at 2:42 PM, Jed Brown <j...@jedbrown.org> wrote: >>>>>> >>>>>>> Matthew Knepley <knep...@gmail.com> writes: >>>>>>> >>>>>>> > On Thu, Sep 25, 2014 at 1:46 PM, Abhyankar, Shrirang G. < >>>>>>> abhy...@mcs.anl.gov >>>>>>> >> wrote: >>>>>>> > >>>>>>> >> You are right. The Jacobian for the power grid application is >>>>>>> indeed >>>>>>> >> non-symmetric. Is that a problem for your application? >>>>>>> >> >>>>>>> > >>>>>>> > If you need a symmetric Jacobian, you can use the BC facility in >>>>>>> > PetscSection, which eliminates the >>>>>>> > variables completely. This is how the FEM examples, like ex12, >>>>>>> work. >>>>>>> >>>>>>> You can also use MatZeroRowsColumns() or do the equivalent >>>>>>> transformation during assembly (my preference). >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> *Miguel Angel Salazar de Troya* >>>>>> Graduate Research Assistant >>>>>> Department of Mechanical Science and Engineering >>>>>> University of Illinois at Urbana-Champaign >>>>>> (217) 550-2360 >>>>>> salaz...@illinois.edu >>>>>> >>>>>> >>>>> >>>>> >>>>> -- >>>>> 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 >>>>> >>>> >>>> >>>> >>>> -- >>>> *Miguel Angel Salazar de Troya* >>>> Graduate Research Assistant >>>> Department of Mechanical Science and Engineering >>>> University of Illinois at Urbana-Champaign >>>> (217) 550-2360 >>>> salaz...@illinois.edu >>>> >>>> >>> >>> >>> -- >>> 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 >>> >> >> >> >> -- >> *Miguel Angel Salazar de Troya* >> Graduate Research Assistant >> Department of Mechanical Science and Engineering >> University of Illinois at Urbana-Champaign >> (217) 550-2360 >> salaz...@illinois.edu >> >> > > > -- > 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 > -- *Miguel Angel Salazar de Troya* Graduate Research Assistant Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign (217) 550-2360 salaz...@illinois.edu