On Apr 17, 2013 6:25 PM, "Dharmendar Reddy" <dharmareddy84 at gmail.com> wrote: > > Sorry, I do not know how the reply went to your id. I replied the usual way. > > > > I am solving : div(grad(V)) = 0 for x in [0, L] and V(0) = V1 and V(L) = V1 > > I get a solution V(x) = V1 after solving with intial guess V(X) = 0 for x in (0, L) > > Now, what is the user defined ? is it V(X) = 0 ? or V(x) = V1 ?
Yes, it is the initial guess. SNES Test does not actually solve the problem. > > Is the user defined state is V(X) = V1 then it means the Jacobin is tested after doing a solve first ? > > But then, for a linear Poisson problem, The Jacobin should be independent of V(X). I seem to get correct solution but snes_type test (fails ?) can you give me some pointers on how to debug this ? How do you define the function evaluation? Is the Jacobian code really independent of the state vector? (It should be.) > > Thanks > > > On Wed, Apr 17, 2013 at 5:55 PM, Dharmendar Reddy <dharmareddy84 at gmail.com> wrote: >> >> I am confused. >> >> I am solving : div(grad(V)) = 0 for x in [0, L] and V(0) = V1 and V(L) = V1 >> >> I get a solution V(x) = V1 after solving with intial guess V(X) = 0 for x in (0, L) >> >> Now, what is the user defined ? is it V(X) = 0 ? or V(x) = V1 ? >> >> Is the user defined state is V(X) = V1 then it means the Jacobin is tested after doing a solve first ? >> >> But then, for a linear Poisson problem, The Jacobin should be independent of V(X). I seem to get correct solution but snes_type test (fails ?) can you give me some pointers on how to debug this ? >> >> Thanks >> Reddy >> >> >> >> >> On Wed, Apr 17, 2013 at 5:36 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote: >>> >>> Dharmendar Reddy <dharmareddy84 at gmail.com> writes: >>> >>> > Hello, >>> > I am solving a one dimensional (linear) Poisson equation. I have >>> > setup a snes problem using DM object. I am using Dirichlet boundary >>> > conditons at both ends of the one dimensional domain. For the test case i >>> > use the same value for potential at both ends. >>> > >>> > I am using DMplex object for the mesh and dof lay out. >>> > >>> > If i run the solver, i get a constant potential profile as expected. >>> > However, If i run the solver with snes_type test >>> > It is giving an error. what could i have done wrong ? >>> > Testing hand-coded Jacobian, if the ratio is >>> > O(1.e-8), the hand-coded Jacobian is probably correct. >>> > Run with -snes_test_display to show difference >>> > of hand-coded and finite difference Jacobian. >>> > Norm of matrix ratio 1.0913e-10 difference 5.85042e-10 (user-defined state) >>> > Norm of matrix ratio 0.5 difference 5.36098 (constant state -1.0) >>> > Norm of matrix ratio 0.666667 difference 10.722 (constant state 1.0) >>> > [0]PETSC ERROR: --------------------- Error Message >>> > ----------------------------------- >>> > - >>> > [0]PETSC ERROR: Object is in wrong state! >>> > [0]PETSC ERROR: SNESTest aborts after Jacobian test! >>> >>> This is what '-snes_type test' is supposed to do. So you're fine and >>> your Jacobian is fine at the initial state, but not at the constant >>> value 1.0 or -1.0. (That's okay if those are non-physical states, >>> otherwise your Jacobian evaluation is incorrect.) >>> >>> > [0]PETSC ERROR: >>> > ----------------------------------------------------------------------- >>> > - >>> > [0]PETSC ERROR: Petsc Development GIT revision: >>> > e0030536e6573667cee5340eb367e8213e67d68 >>> > 9 GIT Date: 2013-04-16 21:48:15 -0500 >>> > [0]PETSC ERROR: See docs/changes/index.html for recent updates. >>> > [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting. >>> > [0]PETSC ERROR: See docs/index.html for manual pages. >>> > [0]PETSC ERROR: >>> > ----------------------------------------------------------------------- >>> > - >>> > [0]PETSC ERROR: ./PoisTest on a mpi_rScalar_Debug named >>> > login2.stampede.tacc.utexas.edu >>> > by Reddy135 Wed Apr 17 17:22:02 2013 >>> > [0]PETSC ERROR: Libraries linked from >>> > /home1/00924/Reddy135/LocalApps/petsc/mpi_rScalar >>> > _Debug/lib >>> > [0]PETSC ERROR: Configure run at Tue Apr 16 22:30:58 2013 >>> > [0]PETSC ERROR: Configure options --download-blacs=1 --download-ctetgen=1 >>> > --download- >>> > metis=1 --download-mumps=1 --download-parmetis=1 --download-scalapack=1 >>> > --download-supe >>> > rlu_dist=1 --download-triangle=1 --download-umfpack=1 >>> > --with-blas-lapack-dir=/opt/apps/ >>> > intel/13/composer_xe_2013.2.146/mkl/lib/intel64/ --with-debugging=1 >>> > --with-mpi-dir=/opt >>> > /apps/intel13/mvapich2/1.9/ --with-petsc-arch=mpi_rScalar_Debug >>> > --with-petsc-dir=/home1 >>> > /00924/Reddy135/LocalApps/petsc PETSC_ARCH=mpi_rScalar_Debug >>> > [0]PETSC ERROR: >>> > ----------------------------------------------------------------------- >>> > - >>> > [0]PETSC ERROR: SNESSolve_Test() line 127 in >>> > /home1/00924/Reddy135/LocalApps/petsc/src/ >>> > snes/impls/test/snestest.c >>> > [0]PETSC ERROR: SNESSolve() line 3755 in >>> > /home1/00924/Reddy135/LocalApps/petsc/src/snes >>> > /interface/snes.c >>> > SNESDivergedReason 0 >>> > Exiting solve >>> > -- >>> > ----------------------------------------------------- >>> > Dharmendar Reddy Palle >>> > Graduate Student >>> > Microelectronics Research center, >>> > University of Texas at Austin, >>> > 10100 Burnet Road, Bldg. 160 >>> > MER 2.608F, TX 78758-4445 >>> > e-mail: dharmareddy84 at gmail.com >>> > Phone: +1-512-350-9082 >>> > United States of America. >>> > Homepage: https://webspace.utexas.edu/~dpr342 >> >> >> >> >> -- >> ----------------------------------------------------- >> Dharmendar Reddy Palle >> Graduate Student >> Microelectronics Research center, >> University of Texas at Austin, >> 10100 Burnet Road, Bldg. 160 >> MER 2.608F, TX 78758-4445 >> e-mail: dharmareddy84 at gmail.com >> Phone: +1-512-350-9082 >> United States of America. >> Homepage: https://webspace.utexas.edu/~dpr342 > > > > > -- > ----------------------------------------------------- > Dharmendar Reddy Palle > Graduate Student > Microelectronics Research center, > University of Texas at Austin, > 10100 Burnet Road, Bldg. 160 > MER 2.608F, TX 78758-4445 > e-mail: dharmareddy84 at gmail.com > Phone: +1-512-350-9082 > United States of America. > Homepage: https://webspace.utexas.edu/~dpr342 -------------- next part -------------- An HTML attachment was scrubbed... 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