Challenge 29 Revisited

Thanks to John Downey, Pedro Graca, Stuart Highman and Kenneth D Weinert for early entries (I've marked the first two and will carry on marking as entries are received). Also, thanks to the commenters regarding the asymmetric distance calculation (not the same distance in each direction!). I found this page on distance calculations

a = pi/2 - lat1
b = pi/2 - lat2
c = sqrt(a^2 + b^2 - 2 * a * b * cos(lon2 - lon1)
d = R * c


Use R= 3956(miles). I know the Earth isn't a sphere- it's an oblate spheroid because the rotation of the Earth makes it bulge slightly at the equator but it's ok for this challenge.

The first times are

1. Pedro Graca 1.567 seconds
2. John Downey 1.658 seconds

Both entries are written in C#.

• Link to Programming Challenge Twenty Nine Manage the Hunters