[petsc-users] Newton methods that converge all the time

Thu Nov 30 08:35:46 CST 2017

On Thu, Nov 30, 2017 at 8:22 AM, Buesing, Henrik <
hbuesing at eonerc.rwth-aachen.de> wrote:

> 1) There should be more to the stack frame. I assume you call
> MatSetValuesStencil(). Do you use PetscFunctionBegin/Return() in that
> function? It would add to the stack
>
>
> [Buesing, Henrik] Yes, I call MatSetValuesStencil(). This is the full
> error. I abort the program after setting MatSetValuesStencil() once. If I
> do not do this, the program runs on, but the Jacobian is assembled wrong.
> The program terminates reaching minimum time step size.
>
>
> 2) I am guessing that you are using a DMDA. There should be an ISL2G there
> automatically. It does not make sense to me that its gone,
>
> and ex19 works that way. The first thing to do to track it down is to get
> the full stack. Then I think we probably need an example small
>
> enough to run here to track through everything, unless you are good with
> teh debugger.
>
> [Buesing, Henrik] Yes, I am using a DMDA. The program does not crash
> abnormally, just does not assemble the Jacobian in a correct way. How would
> I get the full stack?
>

If you can run in the debugger, like gdb, using -start_in_debugger, just
type 'where' when you hit the error.

  Thanks,

    Matt

> Henrik
>
>
>
>   Thanks,
>
>
>
>     Matt
>
>
>
> Thank you!
> Henrik
>
>
>
>
>
>
>
> [1]
>
>
>
> -snes_type ngmres -npc_snes_max_it 1 -snes_converged_reason -npc_snes_type
> fas -npc_fas_coarse_snes_converged_reason -npc_fas_levels_snes_type
> newtonls -npc_fas_levels_snes_max_it 6 -npc_fas_levels_snes_linesearch_type
> basic -npc_fas_levels_snes_max_linear_solve_fail 30
> -npc_fas_levels_ksp_max_it 20 -npc_fas_levels_snes_converged_reason
> -npc_fas_coarse_snes_linesearch_type basic
>
>
>
> [2]
>
>
>
> [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
>
> [0]PETSC ERROR: Null argument, when expecting valid pointer
>
> [0]PETSC ERROR: Null Object: Parameter # 1
>
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> for trouble shooting.
>
> [0]PETSC ERROR: Petsc Release Version 3.8.2, unknown
>
> [0]PETSC ERROR: /rwthfs/rz/cluster/work/hb111949/Descramble/1D_Model/
> steam/JUBE/ngmres/debug/shem_fw64gnu_steam.x on a arch-linux2-c-debug
> named linuxbmc0004.rz.RWTH-Aachen.DE by hb111949 Thu Nov 30 14:35:56 2017
>
> [0]PETSC ERROR: Configure options --download-fblaslapack --with-cc=mpicc
> --with-fc=mpif90 --with-cxx=mpicxx --download-hypre --download-superlu_dist
> --download-suitesparse --download-scalapack --download-blacs
> --download-hdf5 --download-parmetis --download-metis --with-debugging=1
> --download-mumps
>
> [0]PETSC ERROR: #1 ISLocalToGlobalMappingApply() line 639 in
> /rwthfs/rz/cluster/home/hb111949/Code/petsc/src/vec/is/utils/isltog.c
>
> [0]PETSC ERROR: #2 MatSetValuesLocal() line 2139 in
> /rwthfs/rz/cluster/home/hb111949/Code/petsc/src/mat/interface/matrix.c
>
> [0]PETSC ERROR: #3 MatSetValuesStencil() line 1550 in
> /rwthfs/rz/cluster/home/hb111949/Code/petsc/src/mat/interface/matrix.c
>
>
>
>
>
> --
>
> Dipl.-Math. Henrik Büsing
>
> Institute for Applied Geophysics and Geothermal Energy
>
> E.ON Energy Research Center
>
> RWTH Aachen University
>
> ------------------------------------------------------
>
> Mathieustr. 10
> <https://maps.google.com/?q=Mathieustr.+10&entry=gmail&source=g>
> |    Tel +49 (0)241 80 49907 <+49%20241%208049907>
>
> 52074 Aachen, Germany     |    Fax +49 (0)241 80 49889
> <+49%20241%208049889>
>
> ------------------------------------------------------
>
> http://www.eonerc.rwth-aachen.de/GGE
>
> hbuesing at eonerc.rwth-aachen.de
>
> ------------------------------------------------------
>
>
>
> *Von:* Matthew Knepley [mailto:knepley at gmail.com]
> *Gesendet:* 07 November 2017 12:54
> *An:* Buesing, Henrik <hbuesing at eonerc.rwth-aachen.de>
> *Cc:* petsc-users <petsc-users at mcs.anl.gov>
> *Betreff:* Re: [petsc-users] Newton methods that converge all the time
>
>
>
> On Tue, Nov 7, 2017 at 4:19 AM, Buesing, Henrik <
> hbuesing at eonerc.rwth-aachen.de> wrote:
>
> Dear all,
>
>
>
> I am solving a system of nonlinear, transient PDEs. I am using Newton’s
> method in every time step to solve the nonlinear algebraic equations. Of
> course, Newton’s method only converges if the initial guess is sufficiently
> close to the solution.
>
> This is often not the case and Newton’s method diverges. Then, I reduce
> the time step and try again. This can become prohibitively costly, if the
> time steps get very small. I am thus looking for variants of Newton’s
> method, which have a bigger convergence radius or ideally converge all the
> time.
>
>
>
> I tried out the pseudo-timestepping described in
> http://www.mcs.anl.gov/petsc/petsc-current/src/ts/examples/
> tutorials/ex1f.F.html.
>
>
>
> However, this does converge even worse. I am seeing breakdown when I have
> phase changes (e.g. liquid to two-phase).
>
>
>
> I was under the impression that pseudo-timestepping should converge
> better. Thus, my question:
>
> Am I doing something wrong or is it possible that Newton’s method
> converges and pseudo-timestepping does not?
>
> Thank you for any insight on this.
>
>
>
> Hi Hendrik,
>
>
>
> I would try using NGMRES as a nonlinear preconditioner. I have an example
> in my tutorial slides for using it with SNES ex19.
>
> I hope this will work because I suspect that around the phase boundary
> Newton directions are noisy, since sometimes you
>
> step into the other phase. NGMRES takes a few directions (you set the m)
> and then picks the best one.
>
>
>
>   Hopefully this helps,
>
>
>
>      Matt
>
>
>
> Henrik
>
>
>
>
>
> --
>
> Dipl.-Math. Henrik Büsing
>
> Institute for Applied Geophysics and Geothermal Energy
>
> E.ON Energy Research Center
>
> RWTH Aachen University
>
> ------------------------------------------------------
>
> Mathieustr. 10
> <https://maps.google.com/?q=Mathieustr.+10&entry=gmail&source=g>
> |    Tel +49 (0)241 80 49907 <+49%20241%208049907>
>
> 52074 Aachen, Germany     |    Fax +49 (0)241 80 49889
> <+49%20241%208049889>
>
> ------------------------------------------------------
>
> http://www.eonerc.rwth-aachen.de/GGE
>
> hbuesing at eonerc.rwth-aachen.de
>
> ------------------------------------------------------
>
>
>
>
>
>
>
> --
>
> 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
>
>
>
> https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
>
>
>
>
>
> --
>
> 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
>
>
>
> https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
>

-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
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