[QUANTITY] Justification for Matrix Quantities (Was: Re: [QUANTITY] Requirements and apology)

[Brian Thomas]

On Thursday 30 October 2003 10:58 am, Ray Plante wrote:
> >   A quantity is a measurable, countable, or comparable property of
> >   a physical phenomenon that can be represented as a set of numeric
> >   values.  
>
> that is, a quantity can include multiple values.  This was to include
> vectors in simple cartesian space (e.g. magnetic field).  It could also
> handle other simple sets like ranges (although some perhaps "out-of-scope"
> property would be necessary to indicate this).  Multi-dimensional arrays
> could possibly be included, too (e.g. tensors), but I can't think of a
> vital example.

	What about a quantity that has dependence on another one. Consider 
	the search use-case that an astronomer is looking for all flux measurements
	of the visual band. Of course, the search should find those "atomic"
	quantities that are V-band fluxes, but it should *also* beable to find fluxes
	from other flux quantities which are described in terms of wavelength
	(e.g. F(lambda) ) and  where some part of their wavelength range overlaps 
	the visual band (300-700 nm). For these quantities F(l)=> F(300-700nm) == F.

	This example can be further extended to multiple dimensions for quantities.

	=b.t.


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  * Dr. Brian Thomas 

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