Correct.
Specifically, the difference between the two formulas is that one takes into account the curvature of the earth in calculating the distance between point A and point B (without going through each intermediary lon/lat coordinate, a 'straight' calculation would 'pierce' through the earth where it curves, thereby underestimating the distance in varying amounts depending on the distance).
On Apr 27, 2005, at 11:14 AM, Roland Dumas wrote:
So the distances are as the crow flies, right? Not as the Ford drives.
On 4/27/05 7:26 AM, "Chris Millet" <[EMAIL PROTECTED]> wrote:
Stefan,
Here's a simple taf we built to calculate the distance of all stores
within a 100 mile radius of the user. You will need two tables: A
stores table listing all your stores with zip codes and a locator table
listing all the zip codes along with longitude and latitude (we found a
CD online for a small fee). The rest is in the taf itself.
Note: I believe there are a couple of different formulas with varying margins of error. The one we used is the most accurate. It may look confusing, but if you look at it, there are very few variables – just the user's lon/lat coordinates and the radius you want to return, I believe.
Anyway, it shouldn't be difficult once you get the database of zips/lons/lats.
Best, Chris
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