[petsc-users] Fortran interface of MatNullSpaceCreate

[Smith, Barry F.]

> On Feb 26, 2018, at 4:47 PM, frank <hengjiew at uci.edu> wrote:
> 
> Hello,
> 
> It works after changing PETSC_NULL_INTEGER to 0. Thank you so much.
> 
> Does this mean the 3rd argument is a Fortran integer rather than PestcInt?

  No it is actually a PetscInt so technically you should declare

   PetscInt   zero

   zero = 0

   and pass in zero.

   The reason PETSC_NULL_INTEGER doesn't work is 1) it should not be used as a synonym for 0; it is a "pointer" to null not zero 2) PETSC_NULL_INTEGER is actually declared as an array of size 1 (this is why you get the confusing message about no specific subroutine that matches). PETSC_NULL_INTEGER  can only be passed where PETSc expects and integer array, not an integer scalar.

  Barry
 

> 
> Regards,
> 
> Frank
> 
> On 02/26/2018 02:35 PM, Smith, Barry F. wrote:
>>   It should be
>> 
>>> call MatNullSpaceCreate( PETSC_COMM_WORLD, PETSC_TRUE, 0, dummyVecs, nullspace, ierr)
>>   If this doesn't work please send your test code that I can compile myself and figure out what is going on.
>> 
>>   Barry
>> 
>> 
>> 
>> 
>>> On Feb 26, 2018, at 4:18 PM, frank <hengjiew at uci.edu> wrote:
>>> 
>>> Hello,
>>> 
>>> I have a question of the Fortran interface of subroutine MatNullSpaceCreate.
>>> 
>>> I tried to call the subroutine in the following form:
>>> 
>>> Vec                 :: dummyVec, dummyVecs(1)
>>> MatNullSpace :: nullspace
>>> INTEGER         :: ierr
>>> 
>>> (a) call MatNullSpaceCreate( PETSC_COMM_WORLD, PETSC_TRUE, PETSC_NULL_INTEGER, dummyVec, nullspace, ierr)
>>> 
>>> (b) call MatNullSpaceCreate( PETSC_COMM_WORLD, PETSC_TRUE, PETSC_NULL_INTEGER, dummyVecs, nullspace, ierr)
>>> 
>>> (a) and (b) gave me the same error during compilation: no specific subroutine for the generic MatNullSpaceCreate.
>>> 
>>> I am using the latest version of Petsc. I just did a "git pull" and re-build it.
>>> How can I call the subroutine ?
>>> 
>>> In addition, I found two 'petscmat.h90' : petsc/include/petsc/finclude/ftn-auto/petscmat.h90 and petsc/src/mat/f90-mod/petscmat.h90.
>>> The former defines a subroutine MatNullSpaceCreate in the above form (b). The latter provides generic interface for both (a) and (b).
>>> I am not sure if this relates to the error I get.
>>> 
>>> Thank you.
>>> 
>>> Frank
>