# destPoint: Destination given bearing (direction) and distance In geosphere: Spherical Trigonometry

## Description

Given a start point, initial bearing (direction), and distance, this function computes the destination point travelling along a the shortest path on an ellipsoid (the geodesic).

## Usage

 `1` ```destPoint(p, b, d, a=6378137, f=1/298.257223563, ...) ```

## Arguments

 `p` Longitude and Latitude of point(s), in degrees. Can be a vector of two numbers, a matrix of 2 columns (first one is longitude, second is latitude) or a SpatialPoints* object `b` numeric. Bearing (direction) in degrees `d` numeric. Distance in meters `a` major (equatorial) radius of the ellipsoid. The default value is for WGS84 `f` ellipsoid flattening. The default value is for WGS84 `...` additional arguments. If an argument 'r' is supplied, this is taken as the radius of the earth (e.g. 6378137 m) and computations are for a sphere (great circle) instead of an ellipsoid (geodetic). This is for backwards compatibility only

## Value

A pair of coordinates (longitude/latitude)

## Note

Direction changes continuously when travelling along a geodesic. Therefore, the final direction is not the same as the initial direction. You can compute the final direction with `finalBearing` (see examples, below)

## Author(s)

This function calls GeographicLib code by C.F.F. Karney

## References

C.F.F. Karney, 2013. Algorithms for geodesics, J. Geodesy 87: 43-55. https://dx.doi.org/10.1007/s00190-012-0578-z. Addenda: http://geographiclib.sf.net/geod-addenda.html. Also see http://geographiclib.sourceforge.net/

## Examples

 ```1 2 3 4 5 6``` ```p <- cbind(5,52) d <- destPoint(p,30,10000) d #final direction, when arriving at endpoint: finalBearing(d, p) ```

### Example output

```Loading required package: sp
lon      lat
[1,] 5.07293 52.07781
[1] -150
```

geosphere documentation built on July 21, 2018, 3 p.m.