[petsc-dev] Right-preconditioned GMRES

[Pierre Jolivet]

I forgot to mention this, but you just need to run:
mpirun -np 1 ./ex1

Can you reproduce the issue?
Thanks.

> On Feb 9, 2017, at 10:52 PM, Pierre Jolivet <pierre.jolivet at enseeiht.fr> wrote:
> 
> There, attached.
> 
> Thanks.
> 
> PS: here is the patch also, just in case
> diff --git a/src/ksp/ksp/examples/tutorials/ex1.c b/src/ksp/ksp/examples/tutorials/ex1.c
> index 6382c09..d9dc69a 100644
> --- a/src/ksp/ksp/examples/tutorials/ex1.c
> +++ b/src/ksp/ksp/examples/tutorials/ex1.c
> @@ -123,6 +123,11 @@ int main(int argc,char **args)
>      routines.
>    */
>    ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
> +  ierr = KSPSetUp(ksp);CHKERRQ(ierr);
> +  char right_options[] = "-ksp_norm_type unpreconditioned -ksp_pc_side right";
> +  PetscOptionsInsertString(NULL,right_options);
> +  ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
> +  ierr = KSPSetUp(ksp);CHKERRQ(ierr);
> 
>    if (nonzeroguess) {
>      PetscScalar p = .5;
> 
> <ex1.c>
> 
>> On Feb 9, 2017, at 2:56 PM, Matthew Knepley <knepley at gmail.com <mailto:knepley at gmail.com>> wrote:
>> 
>> On Thu, Feb 9, 2017 at 7:48 AM, Pierre Jolivet <pierre.jolivet at enseeiht.fr <mailto:pierre.jolivet at enseeiht.fr>> wrote:
>>> On Feb 9, 2017, at 2:31 PM, Matthew Knepley <knepley at gmail.com <mailto:knepley at gmail.com>> wrote:
>>> 
>>> On Thu, Feb 9, 2017 at 7:29 AM, Pierre Jolivet <pierre.jolivet at enseeiht.fr <mailto:pierre.jolivet at enseeiht.fr>> wrote:
>>> 
>>>> On Feb 9, 2017, at 2:17 PM, Matthew Knepley <knepley at gmail.com <mailto:knepley at gmail.com>> wrote:
>>>> 
>>>> On Thu, Feb 9, 2017 at 7:06 AM, Pierre Jolivet <pierre.jolivet at enseeiht.fr <mailto:pierre.jolivet at enseeiht.fr>> wrote:
>>>> 
>>>>> On Feb 9, 2017, at 1:37 PM, Matthew Knepley <knepley at gmail.com <mailto:knepley at gmail.com>> wrote:
>>>>> 
>>>>> On Thu, Feb 9, 2017 at 4:56 AM, Pierre Jolivet <pierre.jolivet at enseeiht.fr <mailto:pierre.jolivet at enseeiht.fr>> wrote:
>>>>> Hello,
>>>>> I _might_ be doing something wrong when calling KSPSetFromOptions/KSPSetUp, but still, am I supposed to get this kind of error?
>>>>> [0]PETSC ERROR: No support for this operation for this object type
>>>>> [0]PETSC ERROR: KSP gmres does not support PRECONDITIONED with RIGHT
>>>>> 
>>>>> If not, I’ll try to send a MWE (it basically depends on where I set the option -ksp_pc_side right).
>>>>> 
>>>>> I believe its telling you that it cannot display the preconditioned residual with right preconditioning, which is true.
>>>>> Are you requesting both?
>>>> 
>>>> No, I’m just using -ksp_view and -ksp_pc_side right. In the “standard” case, it obviously work.
>>>> However, the error is triggered if I set -ksp_pc_side right after a first call to KSPSetOperators()/KSPSetUp() without destroying the KSP.
>>>> Should I destroy my KSP before changing from left- (default) to right-preconditioning if KSPSetOperators()/KSPSetUp has already been called?
>>>> 
>>>> Its likely you have to use
>>>> 
>>>>   http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetNormType.html <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetNormType.html>
>>>> 
>>>> or
>>>> 
>>>>   -ksp_norm_type unpreconditioned
>>> 
>>> If I use this after my first call to KSPSetUp, I now end up with:
>>> [0]PETSC ERROR: KSP gmres does not support UNPRECONDITIONED with LEFT
>>> 
>>> Yes, you would need to use it at the same time that you change the preconditioning side.
>> 
>> Yes, I’m using PetscOptionsInsert, and whether I let PETSc parse "-ksp_pc_side right -ksp_norm_type unpreconditioned” or "-ksp_norm_type unpreconditioned -ksp_pc_side right” I end up with the same error afterwards.
>> 
>> Can you make an example do it (SNES ex5)? Or can you send a small example that does it?
>> 
>>   Thanks,
>> 
>>     Matt
>>  
>> Thanks.
>> 
>>>   Thanks,
>>> 
>>>      Matt 
>>>> since we would not have a chance to change it since its been set already.
>>>> 
>>>>   Thanks,
>>>> 
>>>>      Matt
>>>> 
>>>> Thanks.
>>>> 
>>>>>   Thanks,
>>>>> 
>>>>>      Matt
>>>>>  
>>>>> Thanks,
>>>>> Pierre
>>>>> 
>>>>> 
>>>>> 
>>>>> -- 
>>>>> 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
>>>> 
>>>> 
>>>> 
>>>> 
>>>> -- 
>>>> 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
>>> 
>>> 
>>> 
>>> 
>>> -- 
>>> 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
>> 
>> 
>> 
>> 
>> -- 
>> 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
> 

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