geosphere-package: Geosphere
Description
This package implements spherical trigonometry functions for geographic applications. There are functions to compute distance and direction (bearing, azimuth, course) along Great Circles (= shortest distance on a sphere, or "as the crow flies") and along rhumb lines (lines of constant direction). There are also funtctions to compute intersections of great circles, and of rhumb lines, and daylength.
Geographic locations must be specified in latitude and longitude in degrees (NOT radians). Degrees are (obviously) in decimal notation. Thus 12 degrees, 30 minutes, 10 seconds = 12 + 10/60 + 30/3600 = 12.175 degrees. The Southern and Western hemispheres have a negative sign.
The default unit of distance is meter; but this can be adjusted by supplying a different radius r to functions.
Directions are expressed in degrees (N = 0 and 360, E = 90, S = 180, and W = 270 degrees).
This is one of the first versions of this package, so please look out for bugs and let us know if you find any.Acknowledgements
David Purdy and Bill Monahan for suggestions to improve the package.References
http://williams.best.vwh.net/avform.htm
http://www.movable-type.co.uk/scripts/latlong.html
http://en.wikipedia.org/wiki/Great_circle_distance
http://mathworld.wolfram.com/SphericalTrigonometry.html