On Thu, May 7, 2009 at 5:24 PM, Jed Brown <jed at 59a2.org> wrote:
> Barry Smith wrote:
>>
>> On May 7, 2009, at 3:00 PM, Lisandro Dalcin wrote:
>
>>> 2) What should happen if a user pass BOTH options -snes_mf and
>>> -snes_mf_operators? Error? One of them should overrides the other?
>>
>> ? ?An error.
>
> The tricky part here is, suppose the user wants to use one of these by
> default, so they put it in a .petscrc or -options_file. ?Now they will
> get an error if they try to change it on the command line.
Although I did not mention it, that was one of the reason I proposed
to add a call for doing this in code...
>?Is there a reasonable way to use whichever option comes last?
AFAIK, no...
> Or just have
> -snes_mf -snes_mf_type {...} so that the options system enforces that
> there is only one way to do it. ?-snes_mf_operator -pc_type none is
> equivalent anyway.
>
Not, it is not equivalent... -snes_mf_operator -pc_type none will
still make a (pointless) call to user's Jacobian routine.
--
Lisandro Dalc?n
---------------
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