[Users] Changes to Multipole

[Ian Hinder]

Hi all,

Multipole is a thorn which provides mode decomposition of grid  
functions into spherical harmonics, and it is part of the Einstein  
Toolkit.  As the thorn is not yet widely used, and we are approaching  
a release of the toolkit, I would like to clean up some aspects of the  
API now before the release.  If there are no objections, I will make  
these changes so that they can be tested as part of the release process.

Currently, Multipole has two modes of operation.  "all modes"  and  
"specific mode" to determine whether a range of modes from l_min to  
l_max are computed, or a single l, m mode.  Some parameters are shared  
between these two methods, and this leads to confusion.  For example,  
if you specify "all modes" (the default, and the one everyone will  
need), then to specify the maximum l_mode you set l_mode = X.  You  
also have to set m_mode otherwise you only get up to m = 2, even  
though you are getting the higher l modes.  I don't think it is  
necessary to have these two modes of operation, and propose to  
simplify the interface so that all modes up to a given l_max are  
computed, for all m.

Specifically:

Deprecate parameters mode_type, l_min, l_mode, m_mode.  Replace with a  
single new parameter l_max.  All modes from l = 0 to l = l_max will be  
computed.  If someone sets l_mode and not l_max, l_mode will be used  
for l_max to keep backward compatibility for a while.

-- 
Ian Hinder
ian.hinder at aei.mpg.de