# ecefOffset

Cartesian ECEF offset between geodetic coordinates

## Syntax

``````[deltaX,deltaY,deltaZ] = ecefOffset(spheroid,lat1,lon1,h1,lat2,lon2,h2)``````
``[] = ecefOffset(___,angleUnit)``

## Description

example

``````[deltaX,deltaY,deltaZ] = ecefOffset(spheroid,lat1,lon1,h1,lat2,lon2,h2)``` returns the Earth-Centered Earth-Fixed (ECEF) Cartesian offset between the geodetic coordinates specified by `lat``1`, `lon``1`, and `h``1` and the coordinates specified by `lat``2`, `lon``2`, and `h``2`. Specify `spheroid` as the reference spheroid for the geodetic coordinates.```
````[] = ecefOffset(___,angleUnit)`, where `angleUnit` is `'radians'`, specifies the units for latitude and longitude as radians. If you do not specify an angle unit, then latitude and longitude are in degrees.```

## Examples

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Find the ECEF offset between Paris, France and Miami, Florida.

First, specify the reference spheroid as WGS 84. For more information about WGS84, see Reference Spheroids. The units for the ellipsoidal height and offset vector must match the units specified by the `LengthUnit` property of the reference spheroid. The default length unit for the reference spheroid created by `wgs84Ellipsoid` is `'meter'`.

`wgs84 = wgs84Ellipsoid;`

Specify the geodetic coordinates of Paris and Miami. Specify `hParis` and `hMiami` as ellipsoidal height in meters. The value of `hMiami` is negative because Miami is below the surface of the reference spheroid.

```latParis = 48.8567; lonParis = 2.3508; hParis = 80; latMiami = 25.7753; lonMiami = -80.2089; hMiami = -25;```

Calculate the ECEF offset between the two geodetic positions. The values `dx`, `dy`, and `dz` are specified in meters. For this example, the results display in scientific notation.

`[dx,dy,dz] = ecefOffset(wgs84,latParis,lonParis,hParis,latMiami,lonMiami,hMiami)`
```dx = -3.2236e+06 ```
```dy = -5.8359e+06 ```
```dz = -2.0235e+06 ```

Calculate the straight-line, 3-D Cartesian distance from Paris to Miami.

`d = norm([dx dy dz])`
```d = 6.9674e+06 ```

## Input Arguments

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Reference spheroid, specified as a `referenceEllipsoid` object, `oblateSpheroid` object, or `referenceSphere` object. The term reference spheroid is used synonymously with reference ellipsoid. To create a reference spheroid, use the creation function for the object. To specify the reference ellipsoid for WGS84, use the `wgs84Ellipsoid` function.

Example: `spheroid = referenceEllipsoid('GRS 80');`

Geodetic latitude of one or more points, specified as a scalar or vector. Specify the values in degrees. To use values in radians, specify the `angleUnit` argument as `'radians'`.

Data Types: `single` | `double`

Geodetic longitude of one or more points, specified as a scalar or vector. Specify the values in degrees. To use values in radians, specify the `angleUnit` argument as `'radians'`.

Data Types: `single` | `double`

Ellipsoidal height of one or more points, specified as a scalar or vector. Specify values in units that match the `LengthUnit` property of the `spheroid` object. For example, the default length unit for the reference ellipsoid created by `wgs84Ellipsoid` is `'meter'`.

For more information about ellipsoidal height, see Find Ellipsoidal Height from Orthometric Height.

Data Types: `single` | `double` | `int8` | `int16` | `int32` | `int64` | `uint8` | `uint16` | `uint32` | `uint64`

Units of the latitude and longitude coordinates, specified as `'degrees'` or `'radians'`.

Data Types: `char`

## Output Arguments

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ECEF offset in the x-axis direction, returned as a scalar or vector. Units are specified by the `LengthUnit` property of the `spheroid` object. For example, the default length unit for the reference ellipsoid created by `wgs84Ellipsoid` is `'meter'`.

ECEF offset in the y-axis direction, returned as a scalar or vector. Units are specified by the `LengthUnit` property of the `spheroid` object. For example, the default length unit for the reference ellipsoid created by `wgs84Ellipsoid` is `'meter'`.

ECEF offset in the z-axis direction, returned as a scalar or vector. Units are specified by the `LengthUnit` property of the `spheroid` object. For example, the default length unit for the reference ellipsoid created by `wgs84Ellipsoid` is `'meter'`.

## Version History

Introduced in R2012b

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