[petsc-dev] MatCreateVecs from Fortran problem

[Matthew Knepley]

On Tue, Mar 17, 2020 at 2:48 PM Mark Adams <mfadams at lbl.gov> wrote:

>
>
> On Tue, Mar 17, 2020 at 2:25 PM Matthew Knepley <knepley at gmail.com> wrote:
>
>> On Tue, Mar 17, 2020 at 2:16 PM Mark Adams <mfadams at lbl.gov> 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
>>>
>>
>> That is wrong.
>>
>>
>>>
>>>
>>>>
>>>> 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
>>>
>>
>> How could v3.7 have the check? If so, you code would be broken.
>>
>
> Barry did it 12 years ago:
>
>
> https://gitlab.com/petsc/petsc/-/commit/7c54600c425fb8d0ad4ad4bb40f7fac17c980c51
>

What you are saying does not make sense. You are saying:

  1) We are passing in NULL Vec objects

  2) Barry put in code to check for such objects

  3) We are getting valid Vec objects back

One of those statement is not true

  Thanks,

     Matt


>
>>
>>> ex73f90t does not initialize the "x" vector that it gives
>>> to matcreatevecs_. Should we just remove initialization of our vectors to
>>> PETSC_NUILL_VEC?
>>>
>>
>> Yes.
>>
>>
>>> 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.
>>>
>>
>> I am not sure what you are asking here.
>>
>
> That we should not initialize our PETSc Vec,Mat,etc. with some sort of
> NULL.  I am sure this is the case.
>
>
>>
>>   Matt
>>
>>
>>> 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/>
>>>>
>>>
>>
>> --
>> 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/>
>>
>

-- 
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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