▲ 4 ▼ A Go implementation of cheapruler for geodesic measurements
"A collection of very fast approximations to common geodesic measurements. Useful for performance-sensitive code that measures things on a city scale.
The approximations are based on an FCC-approved formula of ellipsoidal Earth projection. For distances under 500 kilometers and not on the poles, the results are very precise — within 0.1% margin of error compared to Vincenti formulas, and usually much less for shorter distances."