Re: distance from Easter Island to Chile

[Eli Zaretskii]

> From: Barry Margolin <barmar@alum.mit.edu>
> Date: Sun, 20 Apr 2014 03:01:36 -0400
> 
> In article <mailman.19905.1397975330.10748.help-gnu-emacs@gnu.org>,
>  Eli Zaretskii <eliz@gnu.org> wrote:
> 
> > This is inaccurate (Earth is not a sphere).
> 
> How accurate does your input have to be for that to be a significant? 
> I.e. if you're calculating the distance between two cities, and each 
> city is 5 miles wide, the distance is +/- 10 miles depending on where in 
> the two cities you decide to get the coordinates from. So if the error 
> in the formula is 2 miles, it's less than the inaccuracy in the input, 
> so the formula should be good enough.

No one said that these calculations are only for distances between
large cities.

Anyway, the error induced by assuming spherical Earth can be up to 1%,
which is not insignificant when the distances are on the order of
magnitude of many hundreds of kilometers (3757 km and 4301 km values
were cited by the OP).