[Users] Remove default variable guess from Multipole

[Erik Schnetter]

On Fri, Sep 10, 2010 at 2:00 PM, Ian Hinder <ian.hinder at aei.mpg.de> wrote:
>
> On 10 Sep 2010, at 20:49, Roland Haas wrote:
>
>> Hello all,
>>
>>>> When the Multipole thorn was first written at Penn State for
>>>> debugging, we
>>>> were using it with WeylScal4 and to avoid incompatibilities with
>>>> early
>>>> parameter files, when the "variables" parameter was added we
>>>> decided that if
>>>> it was left blank, it would default to the WeylScal4 Psi4
>>>> variable.  This is
>>>> not a good logical default, as the thorn provides generic mode
>>>> decomposition.  I would like to remove this, and the patch is
>>>> attached.  OK
>>>> to commit?
>> Would it be possible to make the default for the parameter
>> "variables" to be "WeylScal4::Psi4r{sw=-2 cmplx='WeylScal4::Psi4i'
>> name='psi4'}"?
>> I would expect that for most (vacuum) runs done with the code in the
>> Einstein Toolkit one would decompose Psi4 so this default would make
>> sense. Also it would keep the thorn backwards compatible :-)
>
> Sorry - I only saw this message after committing the patch.  What you
> are asking for, as far as I can tell, is the behaviour that was
> implemented.  It has been printing the following warning for 3 years:
>
> WARNING: No Multipole::variables string has been specified.  For
> compatibility, the current default is to use \"WeylScal4::Psi4r{sw=-2
> cmplx=\'WeylScal4::Psi4i\' name=\'psi4\'}\" but in future, this
> default will change to \"\".  Please update your parameter files to
> include this new parameter.
>
> so I think you have had enough time to update parameter files :)

I don't think Roland suggested to have this "silent default" where the
thorn checks for an empty parameter value. I think Roland suggested to
set this as the default value for the parameter, using the standard
Cactus mechanism for this.

Roland, this is a good idea.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/