[petsc-users] clarification of SNES / FormFunction

[Dominik Szczerba]

Because my (class member) functions to construct A(x) and b(x) rely on
the same (class member) "x" as registered with KSP. I could perhaps
set up my A and b routines to take "x" as an argument, but this is a
bit unnatural for a class member function, and I can not quickly
predict the consequences for the rest of the code either.

Dominik

On Tue, May 8, 2012 at 3:22 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> Why a copy?
>
> On May 8, 2012 8:16 AM, "Dominik Szczerba" <dominik at itis.ethz.ch> wrote:
>>
>> >> I am currently assuming they are different and am using the "x" from
>> >> the signature to set up my A(x) and b(x). I was thinking if they are
>> >> the same (i.e. corresponding to x_n in the Newton method), I could
>> >> significantly simplify my code. But apparently "x" in the signature is
>> >> not simply x_n because of the involved line search, correct me if I am
>> >> wrong.
>> >
>> >
>> > Correct, they are not the same. How could it possibly simplify your code
>> > "significantly"?
>>
>> Significantly was perhaps too strong a word, but a vector copy and a
>> couple lines of code would certainly go. Never mind, thanks a lot for
>> the clarification.
>>
>> Dominik