SED Data Model: Questions and Comments

[David Berry]

On Fri, 18 Feb 2005, Sebastien Derriere wrote:

> > It shouldn't be necessary or desirable for everyone to write their own
> > code, since code sharing is presumably what we are about.
>
>   Right, I'm sure there are many other resources (even a 'units' package
> if you're
> running Linux), but the one I'm most familiar with is this one:
> 	http://vizier.u-strasbg.fr/cgi-bin/Unit
> (there's a dimensional analysis of a unit string, among others)
>   And for Java developers, there is a very neat package available here:
> http://cdsweb.u-strasbg.fr/cdsdevcorner/units.gml

I've just put up a facility to http://www.starlink.ac.uk/~dsb/ast/unit-form.html
which uses the AST library to do a dimensional analysis of a given unit
string.

AST can determine and evaluate mappings between any two equivalent
units strings based on FITS-WCS paper I, with a range of tolerated
variations (cm2->cm^2, micron->um, etc). This includes the log, ln, and
exp functions which FITS-WCS paper I specified. But I cannot currently
see how to do a dimensional analysis of say "log(Jy)/sr". Anyone got any
ideas?


David