[petsc-dev] [petsc-maint #49008] Problems with VecDotNorm2

[Barry Smith]

   Satish,

    Can you try to apply solution 1 to 3.1 and see if the tests are ok?

   Barry

On Jul 8, 2010, at 9:56 AM, Jose E. Roman wrote:

> 
> On 07/07/2010, Barry Smith wrote:
> 
>> 
>> On Jul 6, 2010, at 9:49 AM, Jose E. Roman wrote:
>> 
>>> Dear all,
>>> 
>>> We at SLEPc have included a custom implementation of vectors that emulates block vectors in the spirit of PetscExt: v=[v1' v2']' where v1 and v2 are PETSc vectors. This is required for some new SLEPc solvers. With this new type of vectors, we avoid the VecGetArray/VecRestoreArray operations, which would imply array copies, and overload any other required operation. The only place outside SLEPc where these vectors are used is as arguments to KSPSolve.
>>> 
>>> The problem is VecDotNorm2, which is used in KSPSolve_BCGS and KSPSolve_GCR_cycle and invokes VecGetArray. VecDotNorm2 cannot be overloaded as the other functions, since it is not included in the _VecOps table. Therefore we cannot use KSP=bcgsl with our new solvers. A fix for us would be to promote VecDotNorm2 to be a true Vec operation
>> 
>> 
>> I have no objection to upgrading VecDotNorm2() to be a virtual function. 
>> 
>> 
>>> . If possible, it would be nice that the fix would be included in petsc-3.1.
>> 
>>  We really don't like to make such a big change in a patch but if you make the change the change to 3.1 and test it then I have no objection.
>> 
>>  Barry
>> 
>>> 
>>> Thanks,
>>> Jose
>>> 
>>> PS. We plan to release slepc-3.1 in a few weeks.
>>> 
>>> 
>> 
> 
> I am attaching two possible solutions to our problem.
> 
> 1) patch-vecdotnorm2-table.diff --> this is the solution suggested initially. The problem is that if it is included in petsc-3.1 then the ABI will be incompatible with previous patches.
> 
> 2) patch-vecdotnorm2-query.diff --> this uses PetscObjectQueryFunction so that the functionality can be replaced from outside. You may not like this hack but it maintains ABI compatibility.
> 
> You may decide to put 2) into petsc-release-3.1 and 1) into petsc-dev.
> 
> Note that both patchfiles are with respect to petsc-release-3.1.
> 
> Cheers,
> Jose
> 
> 
> <patch-vecdotnorm2-query.diff><patch-vecdotnorm2-table.diff>