# removeLandmark

Remove landmark from state vector

Since R2021b

## Syntax

``removeLandmark(slamObj,landmarkIndex)``

## Description

example

````removeLandmark(slamObj,landmarkIndex)` removes the landmarks at the specified indices `landmarkIndex` from the state vector, along with associated covariances from the state covariance matrix.```

## Examples

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Specify the initial vehicle state.

`initialState = [1; -2; 0.1];`

Specify the initial landmark positions.

```landmarkPosition = [15.8495; -12.9496; 25.2455; -15.4705; 37.5880; 3.1023; 16.5690; 2.7466];```

Specify the initial vehicle state covariance.

`initialStateCovar = diag([0.1*ones(1,3) 1.1*ones(1,8)]);`

Create an `ekfSLAM` object with initial state and initial state covariance.

```ekfSlamObj = ekfSLAM('State',[initialState; landmarkPosition], ... 'StateCovariance',initialStateCovar); landmarkInfo(ekfSlamObj)```
```ans=4×3 table landmark number landmark state index landmark position _______________ ____________________ _________________ 1 4 5 15.85 -12.95 2 6 7 25.245 -15.47 3 8 9 37.588 3.1023 4 10 11 16.569 2.7466 ```

Create a deep copy of the `ekfSLAM` object.

`newEkfSlamObj = copy(ekfSlamObj);`

Specify the landmark number to be removed.

```removeLandmark(newEkfSlamObj,3); landmarkInfo(newEkfSlamObj)```
```ans=3×3 table landmark number landmark state index landmark position _______________ ____________________ _________________ 1 4 5 15.85 -12.95 2 6 7 25.245 -15.47 3 8 9 16.569 2.7466 ```

## Input Arguments

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EKF SLAM object, specified as an `ekfSLAM` object.

Indices of the landmarks to remove, specified as an N-element column vector of landmark numbers in the state vector or an N-by-2 matrix of the exact positions of landmarks in the state vector. N is the number of landmarks to remove.

Data Types: `single` | `double`

## Version History

Introduced in R2021b