# residualgps

Residuals and residual covariance from GPS measurements for `insfilterAsync`

Since R2020a

## Syntax

``[res,resCov] = residualgps(FUSE,position,positionCovariance)``
``[res,resCov] = residualgps(FUSE,position,positionCovariance,velocity,velocityCovariance)``

## Description

example

````[res,resCov] = residualgps(FUSE,position,positionCovariance)` computes the residual, `res`, and the residual covariance, `resCov`, based on the GPS position measurement and covariance.```
````[res,resCov] = residualgps(FUSE,position,positionCovariance,velocity,velocityCovariance)` computes the residual, `res`, and the residual covariance, `resCov`, based on the GPS position measurement and covariance.```

## Examples

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`Create` an `insfilterAsync` object and display its state.

```filter = insfilterAsync; disp(filter.State')```
``` 1.0000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 27.5550 -2.4169 -16.0849 0 0 0 ```

Define GPS data with a position reading and a covariance.

`position = [5 3 2] % in deg deg meters`
```position = 1×3 5 3 2 ```
`positionCovariance = diag([1 1 1]);`

Obtain the residual of the data.

`[res,resCovariance] = residualgps(filter,position,position)`
```res = 1×3 105 × 5.5218 3.3254 0.3282 ```
```resCovariance = 3×3 5.0010 0 0 0 3.0010 0 0 0 2.0010 ```

## Input Arguments

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`insfilterAsync`, specified as an object.

Position of GPS receiver in geodetic latitude, longitude, and altitude (LLA) specified as a real finite 3-element row vector. Latitude and longitude are in degrees with north and east being positive. Altitude is in meters.

Data Types: `single` | `double`

Position measurement covariance of GPS receiver in m2, specified as a 3-by-3 matrix.

Data Types: `single` | `double`

Velocity of the GPS receiver in the local NED coordinate system in m/s, specified as a 3-element row vector.

Data Types: `single` | `double`

Velocity measurement covariance of the GPS receiver in the local NED coordinate system in m2/s2, specified as a 3-by-3 matrix.

Data Types: `single` | `double`

## Output Arguments

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Position and velocity residual, returned as a 1-by-3 vector of real values if the inputs only contain position information, and returned as 1-by-6 vector of real values if the inputs also contain velocity information.

Residual covariance, returned as a 3-by-3 matrix of real values if the inputs only contain position information, and a 6-by-6 matrix of real values if the inputs also contain velocity information.

## Version History

Introduced in R2020a