Re: [SQL] line datatype

On Tuesday 16 July 2002 11:29 am, Thomas Lockhart wrote:
> > > We do need a solution for exact dump/reload of floating-point data,
> > > but I don't see why the lack of it should be reason to disable access
> > > to the LINE type.

> > I don't understand why dumping the two point values isn't sufficient.

> Which two point values? LINE is handled as an equation, not as points,
> unlike the LSEG type which has two points.

> One possibility is to have the external representation *be* the same as
> LSEG, then convert internally. Then we need to decide how to scale those
> points; maybe always using a unit vector is the right thing to do...

Lines are entered now by specifying two points, anywhere on the line, right?  
The internal representation is then slope-intercept?  Why not allow either 
the 'two-point' entry, or direct entry as slope-intercept?  How do we 
represent lines now in output?  Do we pick two arbitrary points on the line?  
If so, I can see Thomas' point here, where the original data entry might have 
specified two relatively distant points -- but then there's a precision error 
anyway converting to slope-intercept, if indeed that is the internal 
representation.  So why not dump in slope-intercept form, if that is the 
internal representation?

But, you're telling me floats aren't dumpable/restoreable to exactly the same 
value?  (????)  This can't be good.
-- 
Lamar Owen
WGCR Internet Radio
1 Peter 4:11