Re: Sessions at Trieste

Sorry Pedro if I did not react in the pre-RFC period, but I imagined I would have time and was suprised you decided so rapidly to start the RFC period.

Even though I'm willing to compromise, let me just comment a bit more on spherical distance functions, summarized by the 2 alternatives  DISTANCE ( POINT( a.coordsys, a.x, a.y), POINT( b.coordsys, b.ra, b.dec))

    and
 sphericalDistance(a.ra, a.dec, b.ra, b.dec)

• even though the functionnalities are similar, I'm not convinced sphericalDistance must be dropped -- the DISTANCE requires the knowledge of the coordinate system which is not easy to find in most, if not all, of the tabular catalogues available right now (in practice it's just defined in some explanatory text) -- while the sphericalDistance just assumes a common coordinate system.
• in terms of implementation, the sphericalDistance function is independent of any region / geometry / STC -- it is just a math function. Therefore why not adding this function ?

By the way, in the DISTANCE expression above, the term "a.coordsys" tends to say that a column in a table could contain the coordinate system and that this system could be different in different rows of a table -- hopefully that is NOT true, and the 'coordsys' would better be seen as a property of a column in a table, written e.g.

    POINT( coordsys(a.x), a.x, a.y)
And as another aside, shouldn't a 'coordsys' property applied on a POINT exist, besides the LONGITUDE and LATITUDE properties ?

While reading the other comments, I also tend to agree that demonstrative examples would help -- for instance if one replaces the dummy numbers in   CIRCLE('ICRS', 1, 2, 3)
by
  CIRCLE('ICRS', a.ra, a.dec, a.diameter/2) this would help the reader, I'm sure.

Also, about the RECTANGLE definition in section 2.3.2.2.5.11 (could it be possible to get rid of such ridiculously wide numbers?), the text mentions "ranges in longitude and latitude" -- which means that a box cannot contain any of the poles. Isn't a rectangle just a particular polygon, joined by great circles ?

Finally, I think a table summarizing the table functions (2.3.2.2.5.x) in a way similar to the math/trigo functions would be quite handy.

But let say again that, besides my comments which I hope are not viewed as only negative, I do appreciate the clarity of the new ADQL document -- and the inclusion of the BNF appendix is really helpful.

--Francois

Francois Ochsenbein       ------       Observatoire Astronomique de Strasbourg
   11, rue de l'Universite F-67000 STRASBOURG       Phone: +33-(0)390 24 24 29
Email: francois-at-astro.u-strasbg.fr   (France)         Fax: +33-(0)390 24 24 32
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