"Wow" <a DeleteThis @alexa.com> wrote in message
news:rj4Nc.1200$KLu1.1070@news04.bloor.is.net.cable.rogers.com...
> > US?
> >
> > How about the official database from the US Census of 2000... is that
good
> > enough?
> >
<font color=green> > > <a style='text-decoration: underline;' href="http://www.census.gov/geo/www/gazetteer/places2k.html</font" target="_blank">http://www.census.gov/geo/www/gazetteer/places2k.html</font</a>>
> >
>
> I have to ask you another question: What is the distance between?
> NH03060 42.748888 -71.464926
> NH03062 42.724822 -71.492388
>
> (42.748888-42.724822)^2+(71.464926-71.492388)^2)^(1/2)*X
> What is X here?
>
Completely irrelevant, because your formula assumes that the Earth is flat
and that lat / long are rectangular co-ordinates (they're "spherical polar
co-ordinates", if you're interested). To save you some work, the formula you
need is:
r * arccos(sin(lat1)sin(lat2) + cos(lat1)cos(long2)cos(long1-long2))
Where r is the radius of the Earth (approx 3963.1 miles).
You need to make sure your programming language of choice is working in the
same angle measurement as the lat / long inputs. Many use radians by
default, while most lat / long figures are quoted in degrees. To convert, if
necessary, radians = degrees * Pi / 180.<!-- ~MESSAGE_AFTER~ -->
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