[petsc-users] Field wise residual norm

[Matthew Knepley]

On Mon, Jan 13, 2014 at 4:53 PM, Dharmendar Reddy
<dharmareddy84 at gmail.com>wrote:

> I may need to read more about those functions to see how i can get the
> norms. But a quick look seem to suggest me that i will need lesser
> function calls than what i am thinking of doing right now.
>
> This is how my approach...Am i doing it right ?
>

This looks like it should work.

  Matt


> subroutine computeResidualNorm(meshDM,F,fieldId,fNorm)
>   implicit none
> #include "finclude/petsc.h90"
>   ! IO Variables
>   DM, intent(inout) :: meshDM
>   Vec, intent(inout) :: F
>   integer, intent(in ) :: fieldId
>   real(WP), intent(inout) :: fNorm
>
>   ! Local Variables
>   PetscErrorCode :: ierr
>   PetscSection :: Section
>   PetscScalar, pointer :: FArray(:)
>   Vec :: gVec, lVec
>   PetscScalar, pointer :: lArray(:)
>   integer :: numFieldDof,offset,dofId
>   integer :: CellId,CellIdStart,CellIdEnd
>   PetscScalar :: zero
>
>   zero = 0.0_WP
>   call DMGetGlobalVector(meshDM, gVec, ierr)
>   call DMGetLocalVector(meshDM, lVec, ierr)
>   call Vecset(lVec, zero, ierr)
>
>   ! Get acess to default section
>   call DMGetDefaultSection(meshDM,section,ierr)
>   ! Get chart
>   call  PetscSectionGetChart(section,cellIdstart,CellIdEnd,ierr)
>   call vecGetArrayF90(F, FArray, ierr)
>   call VecGetArrayF90(lVec, lArray, ierr)
>   do cellId=cellIdstart,cellIdEnd-1
>     call PetscSectionGetFieldDof(section,CellId,fieldId,numFieldDof,ierr)
>     if(numFieldDof > 0) then
>       call PetscSectionGetFieldOffset(section,cellId,fieldId,offset,ierr)
>       do dofId=0,numFieldDof-1
>         ic = offset+dofId
>         lArray(ic) = FArray(ic)
>       end do
>     end if
>   end do
>   call VecRestoreArrayF90(lVec, lArray, ierr)
>   call vecRestoreArrayF90(F, Farray,ierr)
>
>   call DMLocalToGlobalBegin(meshDM, lVec, INSERT_VALUES, gVec, ierr)
>   call DMLocalToGlobalEnd(meshDM, lVec, INSERT_VALUES, gVec, ierr)
>
>   call DMRestoreLocalVector(meshDM, lVec, ierr)
>
>   call VecNorm( gVec, NORM_2, fNorm, ierr)
>
>   call DMRestoreGlobalVector(meshDM, gVec, ierr)
> end subroutine computeResidualNorm
>
> On Mon, Jan 13, 2014 at 4:15 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
> > On Mon, Jan 13, 2014 at 4:11 PM, Dharmendar Reddy <
> dharmareddy84 at gmail.com>
> > wrote:
> >>
> >> Hello,
> >>         Is there a petsc function which can help accomplish the
> following:
> >> I am solving a coupled system of equations:
> >>
> >> F1(x1,x2,x3) = 0
> >>
> >> F2(x1,x2,x3) = 0
> >>
> >> F3(x1,x2,x3) = 0
> >>
> >>
> >> I am using DMPlex to handle to mesh data. I would like to compute the
> >> norm of residual of each function.
> >>
> >> I assemble the function element wise. I am looking for some interface
> >> like,
> >> ComputNorm(dm, F, fieldIndex).
> >
> >
> > Our thinking is generally that you would use
> >
> >   DMCreateSubDM()
> >
> > and then use VecScatterCreate() with the IS it returns. This will map F
> into
> > one of the F1/F2/F3.
> >
> > Does this make sense?
> >
> >    Matt
> >
> >>
> >> Thanks
> >> Reddy
> >
> >
> >
> >
> > --
> > What most experimenters take for granted before they begin their
> experiments
> > is infinitely more interesting than any results to which their
> experiments
> > lead.
> > -- Norbert Wiener
>
>
>
> --
> -----------------------------------------------------
> Dharmendar Reddy Palle
> Graduate Student
> Microelectronics Research center,
> University of Texas at Austin,
> 10100 Burnet Road, Bldg. 160
> MER 2.608F, TX 78758-4445
> e-mail: dharmareddy84 at gmail.com
> Phone: +1-512-350-9082
> United States of America.
> Homepage: https://webspace.utexas.edu/~dpr342
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20140114/8dc2c25e/attachment-0001.html>