diff --git a/README.md b/README.md index 88db769..6ab740e 100644 --- a/README.md +++ b/README.md @@ -6,25 +6,26 @@ The inverse geodesic problem must be solved to compute the distance between two ellipsoid in general. The generalization to ellipsoids, which are not oblate spheroids is not further considered here, hence the term ellipsoid will be used synonymous with oblate spheroid. -The distance between two points is also know as the +The distance between two points is also known as the [Vincenty distance](https://en.wikipedia.org/wiki/Vincenty's_formulae). Here is an example to compute the distance between two points (the poles in this case) on the [WGS 84 ellipsoid](https://en.wikipedia.org/wiki/World_Geodetic_System). import geodesics - let d = try distance((lat: Double.pi / 2,lon: 0), (lat: -Double.pi / 2, lon: 0)) + let d = distance((lat: Double.pi / 2,lon: 0), (lat: -Double.pi / 2, lon: 0)) -and that it. +and that's it. -# Implementation Details +## Implementation Details This Swift package is a wrapper for the [C library for Geodesics 1.49](https://geographiclib.sourceforge.io/html/C/). The author of this library is Charles F. F. Karney (charles@karney.com). The goal of this Swift package is to make some algorithms from [GeographicLib](https://geographiclib.sourceforge.io/) available to the Swift world. -Alternatively one can employ the [vincenty](https://github.com/dastrobu/vincenty) +Alternatively one can employ the package +[vincenty](https://github.com/dastrobu/vincenty) which is a much simpler solver for the inverse geodesic problem, completely written in Swift. Vincenty's formulae does, however, have some convergence problems in rare cases, an may not give the same accuracy as Karney's algorithm. @@ -39,7 +40,7 @@ See documentation of [GeographicLib](https://geographiclib.sourceforge.io/) for By default the [WGS 84 ellipsoid](https://en.wikipedia.org/wiki/World_Geodetic_System) is employed, but different parameters can be specified, e.g. for the -[GRS 80 ellipsoid](https://en.wikipedia.org/wiki/GRS_80) +[GRS 80 ellipsoid](https://en.wikipedia.org/wiki/GRS_80). distance((lat: Double.pi / 2, lon: 0), (lat: -Double.pi / 2, lon: 0), ellipsoid (a: 6378137.0, f: 1/298.257222100882711))