[petsc-users] Dumping KSP solve information to a file

[Barry Smith]

> On Dec 3, 2014, at 7:26 PM, Patrick Sanan <patrick.sanan at gmail.com> wrote:
> 
> I'd like to be able to obtain and process post-solve information about KSP solves, after a PETSc application has run.  Specifically, I would like the information produced by -ksp_converged_reason, as well as the final residual norm, to be available as a file for post-processing.
> 
> A direct approach is to modify the application source, adding my own code invoking KSPGetIterationNumber(), KSPGetConvergedReason(), KSPGetResidualNorm(), etc. to the source, and producing the required output with an ASCII viewer.
> 
> However, it'd be more convenient to be able to obtain the required information without modifying the application source. An inelegant and potentially fragile approach is to provide flags like -ksp_converged_reason, -ksp_monitor, etc. and write a script to extract the required information from what is dumped to stdout.
> 
> My first thought on how to do things properly is to link in my own custom KSP viewer; should that be a viable approach? Is there a simpler/better method?

  We have ways to add your own monitor with KSPMonitorSet() but for viewer basically you would just write your own viewer function and then call it directly.

  Barry

> 
> -Patrick
>