# geoidegm96

Calculate geoid height as determined from EGM96 Geopotential Model

### Note

`geoidegm96` will be removed in a future version. Use `geoidheight` instead.

## Syntax

```N = geoidegm96(lat, long) N = geoidegm96(lat, long, action) ```

## Description

`N = geoidegm96(lat, long)` calculates the geoid height as determined from the EGM96 Geopotential Model. It calculates geoid heights to 0.01 meters. This function interpolates geoid heights from a 15-minute grid of point values in the tide-free system, using the EGM96 Geopotential Model to the degree and order 360. The geoid undulations are relative to the WGS84 ellipsoid.

`N = geoidegm96(lat, long, action)` calculates the geoid height as determined from the EGM96 Geopotential Model. This function performs `action` if `latitude` or `longitude` are out of range.

Inputs required by `geoidegm96`:

 `lat` An array of `m` geocentric latitudes, in degrees, where north latitude is positive and south latitude is negative. `lat` must be of type single or double. If `lat` is not within the range -90 to 90, inclusive, this function wraps the value to be within the range. `long` An array of `m` geocentric longitudes, in degrees, where east longitude is positive and west longitude is negative. `long` must be of type single or double. If `long` is not within the range 0 to 360 inclusive, this function wraps the value to be within the range. `action` Action for out-of-range input. Specify if out-of-range input invokes a `'Warning'`, `'Error'`, or no action (`'None'`). The default is `'Warning'`.

## Examples

Calculate the geoid height at 42.4 degrees N latitude and 71.0 degrees E longitude.

`N = geoidegm96( 42.4, 71.0)`

Calculate the geoid height at two different locations, with out-of-range actions generating warnings.

`N = geoidegm96( [39.3,33.4], [-77.2, 36.5])`

Calculate the geoid height with latitude wrapping, with out-of-range actions displaying no warnings.

`N = geoidegm96(100,150,'None')`

## Limitations

This function has the limitations of the 1996 Earth Geopotential Model. For more information, see `http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/egm96.html`.

The WGS84 EGM96 geoid undulations have an error range of +/-0.5 to +/-1.0 meters worldwide.

## References

NIMA TR8350.2: “Department of Defense World Geodetic System 1984, Its Definition and Relationship with Local Geodetic Systems.”

NASA/TP-1998-206861: “The Development of the Joint NASA GSFC and NIMA Geopotential Model EGM96”

National Geospatial-Intelligence Agency Website: `http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/egm96.html`