[petsc-dev] Recover SNES ex6.c?

[Barry Smith]

On Sep 19, 2012, at 4:48 PM, Karl Rupp <rupp at mcs.anl.gov> wrote:

> Hi,
> 
> as I just noticed, src/snes/examples/tutorials/ex6.c was kicked out two days ago: http://petsc.cs.iit.edu/petsc/petsc-dev/rev/cb006da503e9
> 
> However, ex6.c is included in the user manual, now causing the compilation to fail. With ex6.c containing matrix-free Jacobians, which are not included in ex2.c, the respective section in the manual would require considerable rewriting. Conversely, merging the matrix-free stuff from ex6.c to ex2.c is not an option either, as ex2.c is used elsewhere in the manual, leading to a fairly non-intuitive documentation. Any ideas aside from recovering ex6.c?

   Actually the "ex6.c containing matrix-free Jacobian is kind of bogus because all it does is use the -snes_mf flag which any SNES code can use.

   ex6.c had the additional hodge podge of extra stuff

     0) different matrices for two arguments to SNESSetJacobian() but done in a bogus way
     1) -snes_mf 
      2) storage of snes residual histories
      3) matrix free preconditioner as a shell matrix

  but it does the same model problem as ex2.c so I decided to nuke it.

    I added the matrix free preconditioner as a shell matrix to ex3.c    I didn't see the other extra stuff worth saving. I will edit the users manual to take into account these changes. Thanks for noting the problem.

   Barry



> 
> Best regards,
> Karli