[petsc-users] about Matrix-Free

[behzad baghapour]

OK. Thank you.

On Mon, Jun 4, 2012 at 3:04 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Mon, Jun 4, 2012 at 1:41 AM, behzad baghapour <
> behzad.baghapour at gmail.com> wrote:
>
>> According to my last question, I am trying to use Shell to handle the
>> MatrixFree procedure as below:
>>
>> 1- Define residual as:
>>        F := M * DQ/Dt - R(Q) (R is the nonlinear residual obtained from
>> discretization)
>> 2- MatCreateShell
>> 3- MatShellSetOperation -> MATOP_MULT as follows:
>>        dF/dQ * v = M * v / Dt - ( R(Q+eps*v) - R(Q) ) / eps
>> 4- Using this operation in each step of KSP (GMRES) subspace
>> construction.
>>
>> Does the above procedure seem reasonable to use with SNES? Please help me
>> if it needs more considerations.
>>
>
> You can just set the SNES function and do -snes_mf, then this will be done
> for you.
>
> You might also consider using TS. TSSetIFunction() is the interface you
> propose.
>
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