Re: Going, gone. Removed Sigma Squared.

[Chris Albertson <chris@topdog.pas1.logicon.com>]

aah@nofs.navy.mil wrote:
> 
> Chris wrote that he was removing sigma squared, but leaving mean ra and
> ra sum of squares.  I don't see any problem with that.
>   My question (yes, late, and I'm sorry) is why sum-of-squares is in deg^2.
> You only use this field for calculating sigma later, and for that you use
> the mean ra + nobs fields as well.  Since mean ra is in mas, then a unit
> conversion needs to take place.
>   Why not put sum-of-squares in mas so that everything is consistent?
> Arne

Here is what I was thinking.  It is very easy to change so I'll listen

What we really want is degrees.  I figure what peole using a web site
will see and enter are degress.  We store mas only because it is more
compact. 

The way the software works is it gets its input (from STAR or
whatever) in degrees.  All internal calculation is performed in units
of degrees in 64 bit floats.  We only use mas as a storage format.
I figure the less not stored in degrees the better.

People who access the table directly or write programs that access 
the table need to know what units the columns are in but no one else
should care.  They just see degrees

Another reason is that lately I've thinking about numeric 
precission. I would rather work with numbers in the range of
360.0*360.0 = 1.3E5 then in the range of 
360.0*3600000.0*360.0*3600000.0 = 1.7E18 
 


-- 
--Chris Albertson

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