spherical_angle function

Angle along great circle on spherical surface

Smallest angle between two points on the surface of a sphere, measured along the surface of the sphere

orthodrome(lat1, lon1, lat2, lon2)

haversine(lat1, lon1, lat2, lon2)

vincenty(lat1, lon1, lat2, lon2)

Arguments

• lat1, lat2: numeric vector. latitudes of point 1 and 2 (in radians)
• lon1, lon2: numeric vector. longitudes of point 1 and 2 (in radians)

Returns

numeric. angle in radians

Details

• "orthodrome": based on the spherical law of cosines
• "haversine": uses haversine formula that is optimized for 64-bit floating-point numbers
• "vincenty": uses Vincenty formula for an ellipsoid with equal major and minor axes

Examples

berlin <- c(52.52, 13.41) |> deg2rad()
calgary <- c(51.04, -114.072) |> deg2rad()
orthodrome(berlin[1], berlin[2], calgary[1], calgary[2])
haversine(berlin[1], berlin[2], calgary[1], calgary[2])
vincenty(berlin[1], berlin[2], calgary[1], calgary[2])

References

• Imboden, C. & Imboden, D. (1972). Formel fuer Orthodrome und Loxodrome bei der Berechnung von Richtung und Distanz zwischen Beringungs- und Wiederfundort. Die Vogelwarte 26 , 336-346.

• Sinnott, Roger W. (1984). Virtues of the Haversine. Sky and telescope

  68 (2), 158. Vincenty, T. (1975). Direct and inverse solutions of geodesics on the ellipsoid with application of nested equations. Survey Review, 23 (176), 88<U+2013>93. tools:::Rd_expr_doi("10.1179/sre.1975.23.176.88") .

• http://www.movable-type.co.uk/scripts/latlong.html

• http://www.edwilliams.org/avform147.htm