# n_EA_E_and_n_EB_E2p_AB_E: Find the delta position from two positions A and B In nvctr: The n-vector Approach to Geographical Position Calculations using an Ellipsoidal Model of Earth

## Description

Given the n-vectors for positions A (`n_EA_E`) and B (`n_EB_E`), the output is the delta vector from A to B (`p_AB_E`).

## Usage

 ```1 2 3 4 5 6 7 8``` ```n_EA_E_and_n_EB_E2p_AB_E( n_EA_E, n_EB_E, z_EA = 0, z_EB = 0, a = 6378137, f = 1/298.257223563 ) ```

## Arguments

 `n_EA_E` n-vector of position A, decomposed in E (3x1 vector) (no unit) `n_EB_E` n-vector of position B, decomposed in E (3x1 vector) (no unit) `z_EA` Depth of system A, relative to the ellipsoid (z_EA = -height) (m, default 0) `z_EB` Depth of system B, relative to the ellipsoid (z_EB = -height) (m, default 0) `a` Semi-major axis of the Earth ellipsoid (m, default [WGS-84] 6378137) `f` Flattening of the Earth ellipsoid (no unit, default [WGS-84] 1/298.257223563)

## Details

The calculation is exact, taking the ellipticity of the Earth into account. It is also nonsingular as both n-vector and p-vector are nonsingular (except for the center of the Earth). The default ellipsoid model used is WGS-84, but other ellipsoids (or spheres) might be specified via the optional parameters `a` and `f`.

## Value

Position vector from A to B, decomposed in E (3x1 vector)

## References

Kenneth Gade A Nonsingular Horizontal Position Representation. The Journal of Navigation, Volume 63, Issue 03, pp 395-417, July 2010.

`n_EA_E_and_p_AB_E2n_EB_E`, `p_EB_E2n_EB_E` and `n_EB_E2p_EB_E`
 ```1 2 3 4 5 6 7``` ```lat_EA <- rad(1); lon_EA <- rad(2); z_EA <- 3 lat_EB <- rad(4); lon_EB <- rad(5); z_EB <- 6 n_EA_E <- lat_lon2n_E(lat_EA, lon_EA) n_EB_E <- lat_lon2n_E(lat_EB, lon_EB) n_EA_E_and_n_EB_E2p_AB_E(n_EA_E, n_EB_E, z_EA, z_EB) ```