Vector-valued Quantities

[Ed Shaya]

David,
    You don't need a QuantitySet for what you describe here.  That is 
just an SED with an alternate axis.  And I mentioned that an SED is just 
a Quantity.  You need the set when you combine luminosity and mass for a 
list of stars.  Or for flux and dust extinction along lines of sight.

Ed


David Berry wrote:

>Ed,
>
>  
>
>>    Next we want to combine quantities, but we want to do this keeping
>>some relationship between the index values of both quantities.  This is
>>commonly the case when the nth element in each quantity refer to the
>>same object.  QuantitySet provides for a standard way to get your ducks
>>in a row.
>>    
>>
>
>Given that a CoreQ consists of a Frame and a Mapping (taking a
>ValuesList to be a special form of Mapping), it is represented by:
>
>   CoreQ {
>      Frame f;
>      Mapping m;
>   }
>
>Let's say we have two scalar-valued CoreQ's:
>
>   CoreQ flux
>   CoreQ wavelength;
>
>If we then want to combine these into a single vector-valued CoreQ, do
>we not just join the two Frames together to form a compound Frame,
>and then joing the two Mappings together to form a compound (parallel)
>Mapping, and then combined them in a new CoreQ as follows:
>
>   CoreQ SED {
>      CompoundFrame {
>         flux.f
>         wavelength.f
>      }
>      ParallelMapping {
>         flux.m
>         wavelength.m
>      }
>   }
>
>The above *is* a CoreQ since it is made up of a Frame and a Mapping, so
>why do we need a new "QuantitySet" class?
>
>David
>
>
>  
>