[petsc-users] petsc4py - Convert c example code to Python

Smith, Barry F. bsmith at mcs.anl.gov
Mon Apr 1 10:36:30 CDT 2019

 You are in a very lucky position in terms of debugging because you have a running code you can compare with, take advantage of this fact.

   Ok, you're going to have to see when the two codes start diverging from each other. First run with 

-ts_monitor -snes_monitor -ksp_monitor 

Do the initial values for the monitor match, or do no values match? 

  Put at VecView in both codes on your initial value for x (the initial conditions for the ODE) are they the same?

  Next you should put a VecView() at the end of your IFunction routine and a MatView at the end of your IJacobian routine to make sure they are producing the same values.

 Good luck


> On Apr 1, 2019, at 10:28 AM, Nicola Creati via petsc-users <petsc-users at mcs.anl.gov> wrote:
> The Python and C solutions are different. I used the following commands:
> Python: python ex13.py -ts_max_step 5 -pc_type lu
> C: ./ex13 -ts_max_step 5 -pc_type lu
> I attached the two solutions, values and distributions are different.
> Thanks.
> Nicola
> -- 
> Nicola Creati
> Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS www.inogs.it
> Dipartimento di Geofisica della Litosfera Geophysics of Lithosphere Department
> CARS (Cartography and Remote Sensing) Research Group http://www.inogs.it/Cars/
> Borgo Grotta Gigante 42/c 34010 Sgonico - Trieste - ITALY ncreati at ogs.trieste.it
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> <python_sol.png><c_sol.png>

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