[petsc-users] TSSetIJacobian question

[Mark Adams]

Sorry, I was getting "composite" from DMCompositeGetAccessArray, I am
talking about MatNest.  I can get the matrices with MatNestSetSubMats....

>
> >   ! copy in linear operator
> >   call MatCopy(a_ts%FJacobean,Jpre,ierr);CHKERRQ(ierr)
> >   ! shift 1 & 2 by 'shift'
> >   call MatShift(mat00,shift,ierr);CHKERRQ(ierr)  ????
> >   call MatShift(mat11,shift,ierr);CHKERRQ(ierr)  ????
>
> What does this mean?  Why not include the shift while assembling?
>

Perhaps I am using this incorrectly but the shift is added in
"FormIJacobian" and only 2 of the 3 fields have u_t.  The rest of the
matrix is linear and not time dependant so I create it once in the setup
and copy it in in FormIJacobian.

Thanks,
Mark
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