Dimensionless units

[David Berry]

Sebastien,

> >         It would seem reasonable that a unit conversion scheme should be
> > able to determine the conversion from Jy/sr to Jy/arcmin**2 without needing
> > UCDs.
>
>   And we already have a reasonable answer:
> If I submit this unit ratio: (Jy/sr)/(Jy/arcmin2)
> I get the following
> http://vizier.u-strasbg.fr/cgi-bin/Unit?text=%28Jy%2Fsr%29%2F%28Jy%2Farcmin2%29
> ----> Factor	2.693409339497422e-08;
>   No need of UCD for simple unit scaling problems...

Is the determination of this factor based on a dimensional analysis of the
two units, or is it determined by parsing the units strings?

My point was that, whilst I understand how to do this by parsing the units
strings, I can't see how to do it on the basis of DIMEQ, SCALEQ and UCDs
alone.

David