Re: [petsc-users] Help with KSPSetConvergenceTest

[Stefano Zampini]

Run make allfortranstubs to generate the fortran interfaces,  then make

On Sat, May 13, 2023, 13:35 Edoardo alinovi 
wrote:

> Hello Barry,
>
> I have seen you guys merged in main the minimum tolerance stuff.
>
> After compiling that branch, I have tried to
> call KSPSetMinimumIterations(this%ksp, this%minIter, ierr), but the
> compiler cannot find the function.
>
> I have included this module as standard practice:
> #include "petsc/finclude/petscksp.h"
> use petscksp
>
> Maybe I am missing something else?
>
> Thank you!
>
>
>
>
>

Re: [petsc-users] Help with KSPSetConvergenceTest

[Edoardo alinovi]

Hello Barry,

I have seen you guys merged in main the minimum tolerance stuff.

After compiling that branch, I have tried to
call KSPSetMinimumIterations(this%ksp, this%minIter, ierr), but the
compiler cannot find the function.

I have included this module as standard practice:
#include "petsc/finclude/petscksp.h"
use petscksp

Maybe I am missing something else?

Thank you!

Re: [petsc-users] Help with KSPSetConvergenceTest

[Edoardo alinovi]

Mega! This is gonna be useful for many people :)


Il Mar 9 Mag 2023, 00:54 Barry Smith  ha scritto:

>
>   See https://gitlab.com/petsc/petsc/-/merge_requests/6436 with commit
> barry/2023-05-08/add-ksp-min-its
>
>
>
> On May 7, 2023, at 2:22 PM, Edoardo alinovi 
> wrote:
>
> Hello Barry,
>
> Mega! Thank you Berry much for providing me with a working example! I
> ended up in writing this:
>
>
>
>
>
> *call KSPConvergedDefault(ksp, n, rnorm, flag,
> PETSC_NULL_FUNCTION, ierr)if (n   flag = 0endifierr = 0*
>
> and it looks working but I'll take advantage of your suggestion ;)  Is
> KSPConvergedDefaultDestroy mandatory?
>
> I know it's easy code, but maybe you might have a think to add this
> control and expose it as the max number of iterations in KSP. I can tell
> you it is very much used, I found myself many times in need to tell the
> solver to iterate regardless of the tolerances criteria. It happens for
> example in the RANS equation, especially omega. Sometimes they tend to
> stall and you do want to tighten the tolerances for a bunch of iters, or
> you might not know if they do while iterating!
>
> Cheers
>
>
>

Re: [petsc-users] Help with KSPSetConvergenceTest

[Barry Smith]

  See https://gitlab.com/petsc/petsc/-/merge_requests/6436 with commit 
barry/2023-05-08/add-ksp-min-its 



> On May 7, 2023, at 2:22 PM, Edoardo alinovi  wrote:
> 
> Hello Barry,
> 
> Mega! Thank you Berry much for providing me with a working example! I ended 
> up in writing this:
> 
> call KSPConvergedDefault(ksp, n, rnorm, flag, PETSC_NULL_FUNCTION, 
> ierr)
> if (n flag = 0
> endif
> ierr = 0
> 
> and it looks working but I'll take advantage of your suggestion ;)  Is 
> KSPConvergedDefaultDestroy mandatory?
> 
> I know it's easy code, but maybe you might have a think to add this control 
> and expose it as the max number of iterations in KSP. I can tell you it is 
> very much used, I found myself many times in need to tell the solver to 
> iterate regardless of the tolerances criteria. It happens for example in the 
> RANS equation, especially omega. Sometimes they tend to stall and you do want 
> to tighten the tolerances for a bunch of iters, or you might not know if they 
> do while iterating! 
> 
> Cheers

Re: [petsc-users] Help with KSPSetConvergenceTest

[Edoardo alinovi]

Thanks Barry,

I have fixed the error. Indeed, It's odd it is working. Compiler magic I
guess!

Re: [petsc-users] Help with KSPSetConvergenceTest

[Barry Smith]

> On May 7, 2023, at 2:22 PM, Edoardo alinovi  wrote:
> 
> Hello Barry,
> 
> Mega! Thank you Berry much for providing me with a working example! I ended 
> up in writing this:
> 
> call KSPConvergedDefault(ksp, n, rnorm, flag, PETSC_NULL_FUNCTION, 
> ierr)

This should not work. The argument to KSPConvergedDefault is a context, not a 
function

> if (n flag = 0
> endif
> ierr = 0
> 
> and it looks working but I'll take advantage of your suggestion ;)  Is 
> KSPConvergedDefaultDestroy mandatory?

   You could pass PETSC_NULL_FUNCTION instead of KSPConvergedDefaultDestroy, 
but there is no reason to.

> 
> I know it's easy code, but maybe you might have a think to add this control 
> and expose it as the max number of iterations in KSP. I can tell you it is 
> very much used, I found myself many times in need to tell the solver to 
> iterate regardless of the tolerances criteria. It happens for example in the 
> RANS equation, especially omega. Sometimes they tend to stall and you do want 
> to tighten the tolerances for a bunch of iters, or you might not know if they 
> do while iterating! 
> 
> Cheers

Re: [petsc-users] Help with KSPSetConvergenceTest

[Edoardo alinovi]

Hello Barry,

Mega! Thank you Berry much for providing me with a working example! I ended
up in writing this:





*call KSPConvergedDefault(ksp, n, rnorm, flag, PETSC_NULL_FUNCTION,
ierr)if (n

Re: [petsc-users] Help with KSPSetConvergenceTest

[Barry Smith]

  Working example in 
  https://gitlab.com/petsc/petsc/-/merge_requests/6430

> On May 7, 2023, at 11:47 AM, Barry Smith  wrote:
> 
> 
>   Note, you must call the default test on iteration 0. This is how it 
> determines the initial residual for relative residual tests etc. 
> 
>   I recommend not having the if () test at all. Instead, always call the 
> default convergence test first and then change the flag value it provides if 
> needed before doing any custom checking.
> 
>> On May 7, 2023, at 11:38 AM, Barry Smith  wrote:
>> 
>> 
>>The code will not work as written because KSPConvergedDefault() requires 
>> a context created with KSPConvergedDefaultCreate(). 
>> 
>>Here is a starting point for what you need, in main
>> 
>>integer*8 defaultctx
>>extern MyKSPConverged, KSPConvergedDefaultDestroy
>> 
>> KSPDefaultConvergedCreate(defaultctx,ierr)
>> KSPSetConvergenceTest 
>> (ksp,MyKSPConverged,defaultctx,KSPConvergedDefaultDestroy,
>>  ierr)
>> 
>> 
>> subroutine MyKSPConverged(ksp,n,rnorm,flag,defaultctx,ierr)
>> 
>>KSP  ksp
>>PetscErrorCode ierr
>>PetscInt n
>>integer*8 defaultctx
>>KSPConvergedReason flag
>>PetscReal rnorm
>> 
>>if (n>1) then
>>  call KSPConvergedDefault(ksp, n, rnorm, flag,defaultctx, ierr)
>>else
>>  flag = 0
>>endif
>>ierr = 0
>> 
>> end subroutine MyKSPConverged
>> 
>> 
>> 
>>> On May 7, 2023, at 10:09 AM, Matthew Knepley  wrote:
>>> 
>>> On Sun, May 7, 2023 at 10:02 AM Edoardo alinovi >> > wrote:
 Thanks, 
 
 Is this a reasonable thing to do if I want to replicate what KSP is doing 
 by default?
>>> 
>>> Yes. The other option is to pass along 'dummy'
>>> 
>>>   Thanks,
>>> 
>>> Matt
>>> 
>>> -- 
>>> 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/ 
>> 
> 

Re: [petsc-users] Help with KSPSetConvergenceTest

[Barry Smith]

  Note, you must call the default test on iteration 0. This is how it 
determines the initial residual for relative residual tests etc. 

  I recommend not having the if () test at all. Instead, always call the 
default convergence test first and then change the flag value it provides if 
needed before doing any custom checking.

> On May 7, 2023, at 11:38 AM, Barry Smith  wrote:
> 
> 
>The code will not work as written because KSPConvergedDefault() requires a 
> context created with KSPConvergedDefaultCreate(). 
> 
>Here is a starting point for what you need, in main
> 
>integer*8 defaultctx
>extern MyKSPConverged, KSPConvergedDefaultDestroy
> 
> KSPDefaultConvergedCreate(defaultctx,ierr)
> KSPSetConvergenceTest 
> (ksp,MyKSPConverged,defaultctx,KSPConvergedDefaultDestroy,
>  ierr)
> 
> 
> subroutine MyKSPConverged(ksp,n,rnorm,flag,defaultctx,ierr)
> 
>KSP  ksp
>PetscErrorCode ierr
>PetscInt n
>integer*8 defaultctx
>KSPConvergedReason flag
>PetscReal rnorm
> 
>if (n>1) then
>  call KSPConvergedDefault(ksp, n, rnorm, flag,defaultctx, ierr)
>else
>  flag = 0
>endif
>ierr = 0
> 
> end subroutine MyKSPConverged
> 
> 
> 
>> On May 7, 2023, at 10:09 AM, Matthew Knepley  wrote:
>> 
>> On Sun, May 7, 2023 at 10:02 AM Edoardo alinovi > > wrote:
>>> Thanks, 
>>> 
>>> Is this a reasonable thing to do if I want to replicate what KSP is doing 
>>> by default?
>> 
>> Yes. The other option is to pass along 'dummy'
>> 
>>   Thanks,
>> 
>> Matt
>> 
>> -- 
>> 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/ 
> 

Re: [petsc-users] Help with KSPSetConvergenceTest

[Barry Smith]

   The code will not work as written because KSPConvergedDefault() requires a 
context created with KSPConvergedDefaultCreate(). 

   Here is a starting point for what you need, in main

   integer*8 defaultctx
   extern MyKSPConverged, KSPConvergedDefaultDestroy

KSPDefaultConvergedCreate(defaultctx,ierr)
KSPSetConvergenceTest 
(ksp,MyKSPConverged,defaultctx,KSPConvergedDefaultDestroy,
 ierr)


subroutine MyKSPConverged(ksp,n,rnorm,flag,defaultctx,ierr)

   KSP  ksp
   PetscErrorCode ierr
   PetscInt n
   integer*8 defaultctx
   KSPConvergedReason flag
   PetscReal rnorm

   if (n>1) then
 call KSPConvergedDefault(ksp, n, rnorm, flag,defaultctx, ierr)
   else
 flag = 0
   endif
   ierr = 0

end subroutine MyKSPConverged



> On May 7, 2023, at 10:09 AM, Matthew Knepley  wrote:
> 
> On Sun, May 7, 2023 at 10:02 AM Edoardo alinovi  > wrote:
>> Thanks, 
>> 
>> Is this a reasonable thing to do if I want to replicate what KSP is doing by 
>> default?
> 
> Yes. The other option is to pass along 'dummy'
> 
>   Thanks,
> 
> Matt
> 
> -- 
> 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/ 

Re: [petsc-users] Help with KSPSetConvergenceTest

[Matthew Knepley]

On Sun, May 7, 2023 at 10:02 AM Edoardo alinovi 
wrote:

> Thanks,
>
> Is this a reasonable thing to do if I want to replicate what KSP is doing
> by default?
>

Yes. The other option is to pass along 'dummy'

  Thanks,

Matt

-- 
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/ 

Re: [petsc-users] Help with KSPSetConvergenceTest

[Edoardo alinovi]

Thanks,

Is this a reasonable thing to do if I want to replicate what KSP is doing
by default?

Re: [petsc-users] Help with KSPSetConvergenceTest

[Matthew Knepley]

On Sun, May 7, 2023 at 9:42 AM Edoardo alinovi 
wrote:

> Hi Matt,
>
> h, what if I do:
>
> KSPConvergedDefault(ksp, n, rnorm, flag, PETSC_NULL_FUNCTION, ierr)
>
> That looks to behave OK, but I am not sure about what I am doing -.-
>

You are saying that no convergence context was passed in

  THanks

Matt


> Cheers
>
>

-- 
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/ 

Re: [petsc-users] Help with KSPSetConvergenceTest

[Edoardo alinovi]

Hi Matt,

h, what if I do:

KSPConvergedDefault(ksp, n, rnorm, flag, PETSC_NULL_FUNCTION, ierr)

That looks to behave OK, but I am not sure about what I am doing -.-

Cheers

Re: [petsc-users] Help with KSPSetConvergenceTest

[Matthew Knepley]

On Sun, May 7, 2023 at 9:21 AM Edoardo alinovi 
wrote:

> Hello guys,
>
> Today I am about to write a custom convergence test for KSP doing the
> following job:
>
> - if the number of ksp iterations is less than a given threshold, iterate
> until that threshold is met
> - if the number of ksp iterations is bigger than the threshold, use the
> standard convergence checks.
>
> As far as I understood from the examples, this is the function I need to
> use:
>
> KSPSetConvergenceTest 
> (ksp,MyKSPConverged,0,PETSC_NULL_FUNCTION,ierr)
>
> With MyKSPConverge a subroutine (I am in fortran) where my custom checks are 
> implemented.
>
> Here is how I have coded  MyKSPConverged:
>
>
>
>
>
>
>
>
>
>
>
> *subroutine MyKSPConverged(ksp,n,rnorm,flag,dummy,ierr)   KSP 
>  ksp   PetscErrorCode ierr   PetscInt n,dummy   
> KSPConvergedReason flag   PetscReal rnorm   if (n>1) then 
> call KSPConvergedDefault(ksp, n, rnorm, flag, ierr)*
>
>
Isn't this call missing an argument?

  THanks,

Matt


>
>
>
>
>
> *   else flag = 0   endif   ierr = 0end subroutine 
> MyKSPConverged*
>
> However I get this error:
> [0]PETSC ERROR: KSPSolve has not converged, reason DIVERGED_DTOL
> which I believe to be triggered by *KSPConvergedDefault. *This is odd, as 
> this simulation converge perfectly if I comment ou my dodgy convergence test.
>
> *Do you have any advice for me?*
>
> *thank you! *
>
>
>
>
>
>

-- 
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/