[petsc-dev] GAMG hiding MG -help

[Mark F. Adams]

How about this added to the end of my setoptions:

  ierr = PetscOptionsTail();CHKERRQ(ierr);

static PetscInt nc=0;
if(!nc++)obj->optionsprinted=PETSC_FALSE;

  PetscFunctionReturn(0);
}

Mark


On Mar 19, 2012, at 11:23 PM, Jed Brown wrote:

> On Mon, Mar 19, 2012 at 22:11, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
>  Mark,
> 
>    The problem is all the code Jed added to prevent the same help message from being printed more than once. He added a field to each object, optionsprinted, which gets set once an object is used with PetscObjectOptionsBegin() and prevents printing the next time that same object is used with options. Since the same PC is used for the setfromoptions for gamg and mg the second one mg gets ignored.
> 
>    I cannot see, off hand, the correct fix that respects Jed's desire to have the help messages printed exactly once. You can change PetscObjectOptionsBegin() to PetscOptionsBegin() to get the MG message printed but it will be printed again for each new GAMG setup violating Jed's clean output. You could hide a variable in the _GAMG data structure indicating the help for MG was printed to prevent multiple prints but that is ugly and ideally Jed will point out the correct way to do what you want to do.
> 
> I don't know anything simple. Best would be to make it possible to call PCSetFromOptions_MG() before the number of levels has been set. I don't know if people really want to see the options printed for every level anyway.
> 
> The easiest thing might be to save and restore obj->optionsprinted. (We could make it an integer instead of a PetscBool.)
>  
> 
> 
>   Barry
> 
>   It never bothered me that help messages were printed more than once .....
> 
> It's still a mess, actually. Try running
> 
> $ ./ex5 -snes_grid_sequence 4 -help
> 
> and tell me you are patient enough to scroll up far enough to see a meaningful option.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120320/006ef3c7/attachment.html>