ADQL XMATCH

[Markus Demleitner]

Hi Walter,

On Wed, Apr 06, 2016 at 11:14:17AM -0700, Walter Landry wrote:
> Marco Molinaro <molinaro at oats.inaf.it> wrote:
> 
> Since no one commented on it before, I would like to repeat my
> proposal for a point literal.
> 
>   {a,b} -> POINT('ICRS GEOCENTER',a,b)
> 
> Then the distance function would be
> 
>   DISTANCE({ra1,dec1},{ra2,dec2})
> 
> This would keep the function type safe and obviate the need for a new
> overload for DISTANCE.

I suppose everyone was more or less like me: Nice, but is it really
worth introducing new syntax?  And will this be trouble later, when
we (perhaps) may deal with array literals?  Not sure.  Ah, let
someone else worry about it.

So, I can't give you more than a heartfelt "undecided".


DISTANCE with four floating-point arguments, on the other hand, sits
nicely in my comfort zone of probably making the average astronomer
happy while being very cheap -- after all, we have other functions
that admit a variable number of arguments and change behaviour
depending on the arity used. I'll just mention random here.

Cheers,

         Markus