SNES problem

[JoaoFlavio Vasconcellos]

Dear Lisandro

FormFunction1 is called only once. I'm quite sure that F is  a non zero vector. I'd printed it and its values are 100% rigth.


I've been used snes functions as written above:

...
...
....
                        ierr = SNESCreate(PETSC_COMM_WORLD, &snes);CHKERRQ(ierr);
                        ierr = SNESSetFunction(snes, resid, FormFunction1, this);CHKERRQ(ierr);
....
....                        // Calculating c_ctx.A
....

                        ierr = FormJacobian1(snes, resid, &c_ctx.A, &c_ctx.A, &mat_str, this); CHKERRQ(ierr);
                        ierr = SNESSetJacobian(snes, c_ctx.A, c_ctx.A, FormJacobian1, this); CHKERRQ(ierr);
                        ierr = SNESSetFromOptions(snes);CHKERRQ(ierr);
                         cout << "Calling SNESSolve" << endl;
                         PetscScalar zero = 0;
                         ierr = VecSet(C, zero);CHKERRQ(ierr);
                        ierr = SNESSolve(snes,PETSC_NULL, C);CHKERRQ(ierr);
                        ierr = SNESGetIterationNumber(snes, &its);CHKERRQ(ierr);
                         ierr = SNESGetSolutionUpdate(snes, &C);CHKERRQ(ierr);
                         VecView (C, 0);


...
...
...

    All outputs of VevView in FormFunction1 are ok. The output of VecView (C, 0); after call SNESSolve is an unexpected zero vector.


    Thanks

JF

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


---- Original message ----
>Date: Wed, 3 Oct 2007 12:40:28 -0300
>From: "Lisandro Dalcin" <dalcinl at gmail.com>  
>Subject: Re: SNES problem  
>To: petsc-users at mcs.anl.gov
>
>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)
>PTLC - Güemes 3450, (3000) Santa Fe, Argentina
>Tel/Fax: +54-(0)342-451.1594
>