[petsc-dev] MatCreateVecs from Fortran problem

[Mark Adams]

OK, so we could check if (obj==FORTRAN_TYPE_INITIALIZE) .... and remove all
of our initializations.
And then MatCreateVecs should work.



On Tue, Mar 17, 2020 at 3:52 PM Satish Balay <balay at mcs.anl.gov> wrote:

> Ah - found it. So PETSc is doing this initialization for you.
>
> config/BuildSystem/config/compilersFortran.py:
> help.addArgument('Compilers', '-with-fortran-type-initialize=<bool>',
>  nargs.ArgBool(None, 1, 'Initialize PETSc objects in Fortran'))
> config/BuildSystem/config/compilersFortran.py:
> self.addDefine('FORTRAN_TYPE_INITIALIZE', ' = -2')
> src/vec/f90-mod/petscvec.h:        PetscFortranAddr:: v
> PETSC_FORTRAN_TYPE_INITIALIZE
>
> Satish
>
> On Tue, 17 Mar 2020, Satish Balay wrote:
>
> > The issue is:
> >
> > C has:
> >
> > Vec v=NULL;
> > Vec *v=NULL;
> >
> > However its not clear how to implement this with current f90 interface.
> >
> > I think we currently have:
> >
> > Vec v = PETSC_NULL_VEC = 0 => the second one.
> >
> > What you are looking for is the first one. I see this is automatically
> > set.  I don't see this initialization in petsc - so perhaps the
> > compiler is doing this automatically? [atleast by gfortran]
> >
> > Satish
> >
> > -------------
> >
> > Breakpoint 2, MAIN__ () at ex1f.F90:51
> > 51            x = PETSC_NULL_VEC
> > (gdb) list 33
> > 28      !
> > 29            Vec              x,b,u
> > 30            Mat              A
> > 31            KSP              ksp
> > 32            PC               pc
> > 33            PetscReal        norm,tol
> > 34            PetscErrorCode   ierr
> > 35            PetscInt i,n,col(3),its,i1,i2,i3
> > 36            PetscBool  flg
> > 37            PetscMPIInt size
> > (gdb) p x
> > $2 = ( v = -2 )
> > (gdb) p b
> > $3 = ( v = -2 )
> > (gdb) p u
> > $4 = ( v = -2 )
> > (gdb) p A
> > $5 = ( v = -2 )
> > (gdb) p ksp
> > $6 = ( v = -2 )
> > (gdb) p pc
> > $7 = ( v = -2 )
> > (gdb) c
> > Continuing.
> >
> > Breakpoint 3, MAIN__ () at ex1f.F90:52
> > 52            call MPI_Comm_size(PETSC_COMM_WORLD,size,ierr)
> > (gdb) p x
> > $8 = ( v = 0 )
> > (gdb)
> >
> >
> >
> > On Tue, 17 Mar 2020, Mark Adams wrote:
> >
> > > >
> > > > Passing NULL to MatCreateVecs() means that you do not want a vector
> out:
> > > >
> > > >
> > > Yes, I want both vectors out and we pass it Vec that have been
> initialized
> > > with PETSC_NULL_VEC
> > >
> > >
> > > >
> > > >
> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateVecs.html
> > > >
> > > > I am guessing that this was broken in 3.7 so that it ignored NULL
> input,
> > > > but we fixed that.
> > > >
> > > >
> > > v3.7 has these CHKFORTRANNULLOBJECT. Well the "fix" broke working code
> > >
> > > ex73f90t does not initialize the "x" vector that it gives
> > > to matcreatevecs_. Should we just remove initialization of our vectors
> to
> > > PETSC_NUILL_VEC?
> > >
> > > Is the PETSc model that you don't inialized PETSc object to NULL
> because
> > > you check that pointers are valid PETSc pointers instead of testing on
> > > NULL? So maybe we should remove all these initializations.
> > >
> > > Thanks,
> > > Mark
> > >
> > >
> > > >   Thanks,
> > > >
> > > >     Matt
> > > >
> > > >
> > > >> call MatCreateVecs(solver%KKTmat,solver%xVec2,solver%bVec2,ierr)
> > > >>
> > > >> Petsc code:
> > > >> PETSC_EXTERN void PETSC_STDCALL matcreatevecs_(Mat *mat,Vec
> *right,Vec
> > > >> *left, int *ierr)
> > > >> {
> > > >> PetscPrintf(PETSC_COMM_SELF,"ZZZ 1) matcreatevecs_ start right=%p
> > > >> left=%p\n",right,left);
> > > >>   CHKFORTRANNULLOBJECT(right);
> > > >>   CHKFORTRANNULLOBJECT(left);
> > > >> PetscPrintf(PETSC_COMM_SELF,"ZZZ 2) matcreatevecs_ start right=%p
> > > >> left=%p\n",right,left);
> > > >>   *ierr = MatCreateVecs(*mat,right,left);
> > > >> }
> > > >>
> > > >> produces this:
> > > >>
> > > >> ZZZ 1) matcreatevecs_ start right=0x7fffffff3758 left=0x7fffffff3760
> > > >> ZZZ 2) matcreatevecs_ start right=(nil) left=(nil)
> > > >>
> > > >> Shouldn't  this be?
> > > >>
> > > >> PETSC_EXTERN void PETSC_STDCALL matcreatevecs_(Mat *mat,Vec
> *right,Vec
> > > >> *left, int *ierr)
> > > >> {
> > > >>   *ierr = MatCreateVecs(*mat,right,left);
> > > >> }
> > > >>
> > > >>
> > > >
> > > > --
> > > > 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
> > > >
> > > > https://www.cse.buffalo.edu/~knepley/
> > > > <http://www.cse.buffalo.edu/~knepley/>
> > > >
> > >
> >
> >
>
>
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