[petsc-users] function set by TSSetRHSJacobian() not being called

[Scott Dossa]

Hi all,

I adapted ex13.c from .../ts/examples/tutorials/ex13.c to solve a 1D TD PDE
(swift-hohenberg).
*Long story short*: the function which sets the Jacobian is never being
called despite being assigned by TSSetRHSJacobian().

I create the TS environment with the following commands (omitting some code
before and after -- Full code attached):

---------------------------------------------------------------------------------------------------------------------------------------------------------------------
  ierr = DMDACreate1d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, 15, 1, 1, NULL,
&da); CHKERRQ(ierr);


/*==================================================================

    Let DMDA create
vector

    ==================================================================*/

  ierr = DMCreateGlobalVector(da, &x);CHKERRQ(ierr);


/*==================================================================

    Create timestepper context which will use Euler
Method

    ==================================================================*/

  ierr = TSCreate(PETSC_COMM_WORLD,&ts);CHKERRQ(ierr);
  ierr = TSSetDM(ts, da);CHKERRQ(ierr);
  ierr = TSSetType(ts, TSEULER);CHKERRQ(ierr);

  ierr = TSSetRHSFunction(ts, x, RHSFunction, NULL);CHKERRQ(ierr);


/*=================================================================

    Create Jacobian for Euler
Method

    =================================================================*/
  ierr = DMSetMatType(da, MATAIJ);CHKERRQ(ierr);
  ierr = DMCreateMatrix(da,&J);CHKERRQ(ierr);
  ierr = TSSetRHSJacobian(ts,J,J,RHSJacobian,NULL); CHKERRQ(ierr)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------

I define the function RHSJacobian later, PetscPrintf(PETSC_COMM_WORLD,
"Jacobian function called") is used to see if the function is ever called.

Neither is the message ever called, nor is the Jacobian matrix ever
non-zero. The J matrix is checked with MatView( ). No error messages are
produced either at compiling nor runtime.

Has anyone else run into such an issue or have any advice of how best to
probe the problem?
Thanks so much!
-Scott Dossa
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