[petsc-users] Setting absolute tolerance on ksp solver

[Barry Smith]

  Instead of setting rtol to default you should set it zero so it never gets triggered.

> On Sep 8, 2015, at 10:38 PM, Amal Sahai <amalsahai at gmail.com> wrote:
> 
> I have been setting the tolerance for a ksp solver using KSPSetTolerances. I would like to set my convergence criteria using only the absolute convergence parameter. I use the following command to set this up:
> 
> KSPSetTolerances( ksp, PETSC_DEFAULT, atol, PETSC_DEFAULT, maxits)
> 
> The problem is my ksp solver considers only the value of rtol while stopping the iterative solve. I tried changing the value of rtol to some other parameter instead of PETSC_DEFAULT (while making sure that atol is the more stringent condition requiring more iterations) but to no avail.
> 
> How can I fix this?
> 
> Regards
> Amal