>>>>
>>>>The formula is unnamed, but is indicated as being the most accurate.
>>>>
>>>This one looks simplier (from Fox2x samples):
>>
>>Simpler isn't always better. "Samples" are seldom the best practice.
>>
>>The wikipedia page says the third formula is the most accurate and that the others have large rounding errors at close distances.
>>
>>Thanks
>
>Wikipedia says:) Did you really see that rounding error?

Cetin. You are trusting that the fox2x sample is correct? Do you know it is?

I just went here: http://www.acscdg.com/

It's got a weird UI, Set it to miles. Enter my address: 120 parsell square toronto M1B 2A6 click find. The point will appear. Click start a course. Click on the point and an X appears and it is listed as point 0 in the left.

Now enter 16 william kitchen blvd M1P 2B7 and click find. This second point appears. Click on this point and a new X appears. It will be listed as point 1. The distance is shown as 3.7 miles. Click end at last point.

The formula Naomi referred to and you provided in message #1052327 should have converted degrees to radians. I almost dismissed it because I can tell you from personal experience 16 William Kitchen Blvd is not 271 miles from my house. :)

I see in the one you just provided you converted degrees to radians. The two formulae are producing the same results for these pairs (my address and 125 parsell) 43.797283,-79.214771,43.797293,-79.214723 with SET DECIMALS TO 10

According to both calculations the distance is .004 miles or 21 feet. The two addresses are approximately 100 feet apart.

Unfortunately I cannot obtain known examples of long/lat pairs with higher precision than those.