SNES problem

[Lisandro Dalcin]

Flavio, are you completelly sure your FormFunction1() is actually
being called? I can see the SNES monitor at iter 0, but I did not see
in the the outputs of VecView() or your 'cout << "Residual " << endl'.
Did you called SNESSetFunction() to set your FormFunction1()??

On 10/3/07, JoaoFlavio Vasconcellos <joaoflavio.vasconcellos at jcu.edu.au> wrote:
> Hello
>
> I'm trying to use SNES to solve a problem. I wrote the code above to evaluate the residual of the linear system. In this routine norm_2 of F is different from zero but outside of this routine norm_2 of F is zero.
>
> #undef __FUNCT__
> #define __FUNCT__ "FormFunction1"
> PetscErrorCode FormFunction1(SNES snes, Vec X, Vec F, void *_simulator) {
> Simulator   *simulator = (Simulator*) _simulator;
> PetscErrorCode ierr;
>
>         VecView (X, 0);
>         ierr = simulator->CalculateMatrixCoefficient(X); CHKERRQ(ierr);
>         ierr = simulator->CalculateSourceTerm(X); CHKERRQ(ierr);
>         ierr = simulator->CalculateResidual (X, &F); CHKERRQ(ierr);
>
>         cout << "Residual " << endl;
>         VecView (F, 0);  // norm_2 of F is != zero
>         return 0;
>
> }
>
> // End of routine
>
>
>
>
> Messages from  -snes_view:
>
>  0 SNES Function norm 0.000000000000e+00
> SNES Object:
>   type: ls
>     line search variant: SNESLineSearchCubic
>     alpha=0.0001, maxstep=1e+08, steptol=1e-12
>   maximum iterations=50, maximum function evaluations=10000
>   tolerances: relative=1e-08, absolute=1e-50, solution=1e-08
>   total number of linear solver iterations=0
>   total number of function evaluations=1
>   KSP Object:
>     type: gmres
>       GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement
>       GMRES: happy breakdown tolerance 1e-30
>     maximum iterations=10000, initial guess is zero
>     tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
>     left preconditioning
>   PC Object:
>     type: ilu
>       ILU: 0 levels of fill
>       ILU: factor fill ratio allocated 1
>       ILU: tolerance for zero pivot 1e-12
>            out-of-place factorization
>            matrix ordering: natural
>
> // end of message
>
> I dont know why  "SNES Function norm 0.000000000000e+00" if
> F's norm_2 inside my routine is not.  Has anyone that could sugest how to fix this problem ?
>
>
> Thank you in advance.
>
>
> Joao Flavio Vieira de Vasconcellos
> School of Engineering
> James Cook University
>
> Phone:  +61 7 4781 4340
> Fax:    +61 7 4775 1184
> Email:  jflavio at iprj.uerj.br
>         joaoflavio.vasconcellos at jcu.edu.au
> skype:  jflavio_vasconcellos
> msn:    jf_vasconcellos at hotmail.com
>
>


-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
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