Problem with SNESSolve()

[Matthew Knepley]

The error says the the object 'x', the solution vector, has an incorrect header
in the call. Since I see you have created the vector, the most likely
explanation
is overwriting memory in computeFunction or computeJacobian, however these
functions are not in the mail.

Also, I would suggest that you move to the local fnuction paradigm if you are
using DAs. See SNES ex5 for an example. This is much easier to code and
results in fewer memory overwrites.

  Thanks,

     Matt

On Mon, Mar 10, 2008 at 6:24 AM, Rafael Santos Coelho
<rafaelsantoscoelho at gmail.com> wrote:
> Hello, guys! (:
>
> I've been trying to code a program that solves a simple 3D
> diffusion-convection problem, but there's something weird going on. Whenever
> I run it, I get the following error message:
>
> $ mpirun -np 1 ./ex8 -x 8 -y 8 -z 8
>  [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [0]PETSC ERROR: Invalid argument!
> [0]PETSC ERROR: Wrong type of object: Parameter # 2!
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
>  [0]PETSC ERROR: VecMaxPointwiseDivide() line 35 in
> src/vec/vec/interface/rvector.c
> [0]PETSC ERROR: SNESLineSearchCubic() line 544 in src/snes/impls/ls/ls.c
> [0]PETSC ERROR: SNESSolve_LS() line 211 in src/snes/impls/ls/ls.c
>  [0]PETSC ERROR: SNESSolve() line 1871 in src/snes/interface/snes.c
> [0]PETSC ERROR: main() line 135 in src/snes/examples/tutorials/ex8.c
>
> Well, line 135 is:
>    ierr = SNESSolve(snes, PETSC_NULL, x); CHKERRQ(ierr);
>
> Here's the main function: (I removed several comments of mine to make it
> smaller)
>
> typedef struct {
>    DA da;
> } appContext;
>
> PetscScalar Hx, Hy, Hz, Hx2, Hy2, Hz2;
> PetscInt M = 9, N = 9, P = 9;
>
> #undef __FUNCT__
> #define __FUNCT__ "main"
>
> int main(int argc, char **argv) {
>    SNES snes;
>    Mat J;
>    appContext ctx;
>    Vec x, r;
>    PetscErrorCode ierr;
>    PetscScalar hx, hy, hz;
>
>    PetscInitialize(&argc, &argv, (char*) 0, help);
>
>    ierr = PetscOptionsGetInt(PETSC_NULL, "-y", &M, PETSC_NULL);
> CHKERRQ(ierr);
>    ierr = PetscOptionsGetInt(PETSC_NULL, "-x", &N, PETSC_NULL);
> CHKERRQ(ierr);
>     ierr = PetscOptionsGetInt(PETSC_NULL, "-z", &P, PETSC_NULL);
> CHKERRQ(ierr);
>
>    hx = 1.0 / (N+1); hy = 1.0 / (M+1); hz = 1.0 / (P+1);
>
> // global variables
>    Hx2 = 1.0 / (2.0*hx*hx); Hy2 = 1.0 / (2.0*hy*hy); Hz2 = 1.0 /
> (2.0*hz*hz);
>     Hx = 1.0 / (hx*hx); Hy = 1.0 / (hy*hy); Hz = 1.0 / (hz*hz);
>
>    ierr = SNESCreate(PETSC_COMM_WORLD, &snes); CHKERRQ(ierr);
>
>    ierr = DACreate3d(PETSC_COMM_WORLD, DA_NONPERIODIC, DA_STENCIL_STAR, M,
> N, P, PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE, 1, 1, PETSC_NULL,
> PETSC_NULL, PETSC_NULL, &ctx.da);
>
>    ierr = DACreateGlobalVector(ctx.da, &x); CHKERRQ(ierr);
>    ierr = VecDuplicate(x, &r); CHKERRQ(ierr);
>
>    ierr = DAGetMatrix(ctx.da, MATAIJ, &J); CHKERRQ(ierr);
>
>    ierr = SNESSetFunction(snes, r, computeFVector, &ctx); CHKERRQ(ierr);
>    ierr = SNESSetJacobian(snes, J, J, computeJacobian, &ctx); CHKERRQ(ierr);
>
>    ierr = SNESSetFromOptions(snes); CHKERRQ(ierr);
>
>    ierr = formInitialGuess(x); CHKERRQ(ierr);
>    ierr = SNESSolve(snes, PETSC_NULL, x); CHKERRQ(ierr);
>
>    ierr = VecDestroy(x); CHKERRQ(ierr);
>    ierr = VecDestroy(r); CHKERRQ(ierr);
>    ierr = MatDestroy(J); CHKERRQ(ierr);
>    ierr = SNESDestroy(snes); CHKERRQ(ierr);
>    ierr = DADestroy(ctx.da); CHKERRQ(ierr);
>     ierr = PetscFinalize(); CHKERRQ(ierr);
>
>    PetscFunctionReturn(0);
> }
>
>
> What am I missing here?
>
> Regards,
>
> Rafael Santos Coelho
>



-- 
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