Question

I’m making an application for tracking a user as they run, cycle or walk and display it to the screen.
I know that there is distanceBetween function built into android but is this accurate enough for a fittness application?
I was considering using Haversine formula or other such formula for calculating distances between points the only problem I see about these formulas is that it usually is straight line or as the crow flys distances.
Does anyone have an idea about this?

Answer 1

The Haversine formula is accurate for most distances, but it suffers from rounding errors when the points are (nearly) antipodal. The following formula is accurate for all distances.

> double delta = G1 - G2;  
>     double p1 = cos(L2) * sin(delta);
>     double p2 = cos(L1) * sin(L2) - sin(L1) * cos(L2) * cos(delta);  
>     double p3 = sin(L1) * sin(L2) + cos(L1) * cos(L2) * cos(delta);
>     distance = 60 * Math.atan2(Math.sqrt(p1*p1 + p2*p2), p3);

Here’s an example and the implementation.

resource : Here