Radius search

[Kesterson, Roger]

Good old Pythagoras is fine as long as you have a close approximation of the
distance per degree of longitude, since the lines of longitude converge as
you approach the poles.  See the SupportLink article...

> -----Original Message-----
> From: Chris Sharman [mailto:Chris.Sharman@ccagroup.co.uk]
> Sent: Monday, November 06, 2000 2:26 AM
> To: jpearce@rmi.net
> Cc: Chris.Sharman@ccagroup.co.uk; powerh-l@sphere.swau.edu
> Subject: RE: Radius search
> 
> You shouldn't need complicated math: good old Pythagoras is 
> good enough for
> small distances (ie approximating to flat & not too much 
> variation in the
> length of arc subtended by 1 degree East).
> 
> x*x + y*y = z*z
> 
> where x, y, z are the sides of a right-angled triangle.
> 
> Eg: x is the relative Easting, y is the relative Northing, 
> then z will be the
> distance "as the crow flies".
> 
> There's no sqrt function either of course, but you could 
> select all with
> z*z <= 10000, and put them in distance order.
> 
> Chris
> ______________________________________________________________
> _________
> Chris.Sharman@CCAgroup.co.uk		http://www.ccagroup.co.uk/
> CCA Stationery Ltd, Eastway, Fulwood, Preston, Lancashire, PR2 9WS.
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