Unset parameters should not be written to file

[Corrado Maurini]

The parameters profile and convergence_norm_type of PETScKrylovSolver are unset. This causes the following error when saving the parameters to a file:

*** -------------------------------------------------------------------------
*** DOLFIN encountered an error. If you are not able to resolve this issue
*** using the information listed below, you can ask for help at
***
***     [e-mail]
***
*** Remember to include the error message listed below and, if possible,
*** include a *minimal* running example to reproduce the error.
***
*** -------------------------------------------------------------------------
*** Error:   Unable to convert parameter to string .
*** Reason:  Parameter has not been set.
*** Where:   This error was encountered inside Parameter.cpp.
*** Process: unknown
*** 
*** DOLFIN version: 1.3.0+
*** Git changeset:  13c0b37b7fc8f69a6de0eb0df104838c9c7c49ff
*** -------------------------------------------------------------------------

A minimal example to reproduce the error:

tmp = PETScKrylovSolver()
p = tmp.parameters
info(p, True)
File("parameters.xml") << p

If I try to set the profile option, the solver does not work any more (it runs without giving error messages, but it does not perform any iteration).

[Corrado Maurini]

@garth-wells The most important part of the bug has been introduced here. Is there a rationale in this commit?

Is it possible to revert to the previous version?

[Jan Blechta]

profile works for me.

[Prof Garth Wells]

Is this still a bug?

[Tianyi Li]

Yes, can be reproduced.

[Corrado Maurini]

Yes, I think that unset parameters should be classified as a bug. The code snippet above saving the parameters to a file still gives the reported error. Below the output of PETScKrylovSolver default parameters. convergence_norm_type and profile should have default values.

  petsc_krylov_solver      |    type    value                         range  access  change
  -----------------------------------------------------------------------------------------
  absolute_tolerance       |  double    1e-15                            []       0       0
  convergence_norm_type    |  string  <unset>  [none, preconditioned, true]       0       0
  divergence_limit         |  double    10000                            []       0       0
  error_on_nonconvergence  |    bool     true                 {true, false}       0       0
  maximum_iterations       |     int    10000                            []       0       0
  monitor_convergence      |    bool    false                 {true, false}       0       0
  nonzero_initial_guess    |    bool    false                 {true, false}       0       0
  options_prefix           |  string  default                            []       0       0
  profile                  |    bool  <unset>                 {true, false}       0       0
  relative_tolerance       |  double    1e-06                            []       0       0
  report                   |    bool     true                 {true, false}       0       0
  use_petsc_cusp_hack      |    bool    false                 {true, false}       0       0

[Prof Garth Wells]

Do not attempt to write unset parameters to file. Fixes Issue #259.

→ <<cset e6e60e4910af>>

[Prof Garth Wells]

This bug doesn't have anything to do with the PETSc wrapper. This issue was that DOLFIN attempted to write unset parameters to file, which since unset parameters do not have a value lead to an error.

[Martin Sandve Alnæs]

Removing milestone: 1.6 (automated comment)