I think the current code is to support:
if (var not initialized): crate(var).
And there might be some mapping of 0 to NULL or some other state (hence the
choice of -2)
Satish
On Tue, 2 Feb 2021, Barry Smith wrote:
>
> I cannot remember why I selected -2 as the initial value for PETSc objects
> in Fortran. Probably because it would ensure a dramatic crash if you used
> an object without initializing it from Fortran.
>
> It could be changing
>
> config/BuildSystem/config/compilersFortran.py:
> self.addDefine('FORTRAN_TYPE_INITIALIZE', ' = -2')
>
> to 0 would mean that if you called destroy on the object and never created it
> everything would be fine; so you would not need to use any special code to
> check.
>
> Would that be a better model?
>
> Barry
>
>
>
> > On Feb 2, 2021, at 2:34 PM, Mark Adams <[email protected]> wrote:
> >
> > Thanks Randy, that makes sense.
> > Mark
> >
> > On Tue, Feb 2, 2021 at 3:27 PM Randall Mackie <[email protected]
> > <mailto:[email protected]>> wrote:
> > Hi Mark,
> >
> > I don’t know what the XGC code is, but the way I do this in my Fortran code
> > is that I initialize all objects I later want to destroy, for example:
> >
> > mat11=PETSC_NULL_MAT
> > vec1=PETSC_NULL_VEC
> >
> > etc
> >
> > Then I check and destroy like:
> >
> > if (mat11 /= PETSC_NULL_MAT) call MatDestroy(mat11, ierr)
> >
> > etc.
> >
> > Hope this helps,
> >
> > Randy
> >
> >
> > > On Feb 2, 2021, at 12:17 PM, Mark Adams <[email protected]
> > > <mailto:[email protected]>> wrote:
> > >
> > > Satish, a few years ago you helped us transition the XGC Fortran code
> > > from v3.7.7 and we seemed to have regressed.
> > >
> > > As I recall we removed the initialization of Mats (for example) in XGC.
> > > PETSc seems to initialize them with -2 in Fortran (Albert, cc'ed,
> > > verified this today) and I recall that from our previous conversation. As
> > > I look at the code now Fortran MatDestroy just goes straight to C, which
> > > would explain our crashes when we MatDestroy an uninitialized (-2) Mat.
> > >
> > > What is the correct way to delete with initializing Fortran objects?
> > >
> > > Thanks,
> > > Mark
> > >
> > >
> >
>
>
