# polarMotion

Calculate Earth polar motion

Since R2018b

## Syntax

``polarmotion=polarMotion(utc)``
``[polarmotion,polarmotionError]=polarMotion(utc)``
``polarmotion=polarMotion(utc,Name,Value)``
``[polarmotion,polarmotionError]=polarMotion(utc,Name,Value)``

## Description

example

````polarmotion=polarMotion(utc)` calculates the movement of the rotation axis with respect to the crust of the Earth for a specific Coordinated Universal Time (UTC), specified as a modified Julian date. By default, this function uses a prepopulated list of IAU 2000A Earth orientation (IERS) data. This list contains measured and calculated (predicted) data supplied by the IERS. The IERS measures and calculates this data for a set of predetermined dates. `[polarmotion,polarmotionError]=polarMotion(utc)` calculates the error for the movement of the rotation axis with respect to the crust of the Earth.```

example

````polarmotion=polarMotion(utc,Name,Value)` calculates the movement of the rotation axis with respect to the crust of the Earth using additional options specified by one or more `Name,Value` pair arguments.`[polarmotion,polarmotionError]=polarMotion(utc,Name,Value)` calculates the error for the movement of the rotation axis with respect to the crust of the Earth. ```

## Examples

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Calculate the polar motion for December 28, 2015.

```mjd = mjuliandate(2015,12,28) polarmotion = polarMotion(mjd) ```
```mjd = 57384 polarmotion = 1.0e-05 * 0.0289 0.1233```

Calculate the polar motion and polar motion error for December 28, 2015 and January 10, 2016 using the `aeroiersdata.mat` file. Use the `mjuliandate` function to calculate the date as a modified Julian date.

```mjd = mjuliandate([2015 12 28;2016 1 10]) [polarmotion,polarmotionErr] = polarMotion(mjd,'Source','aeroiersdata.mat')```
```mjd = 57384 57397 polarmotion = 1.0e-05 * 0.0289 0.1233 0.0174 0.1304```

## Input Arguments

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Array of UTC dates, specified as an M-by-1 array, represented as modified Julian dates. Use the `mjuliandate` function to convert the UTC date to a modified Julian date.

Data Types: `double`

### Name-Value Arguments

Specify optional pairs of arguments as `Name1=Value1,...,NameN=ValueN`, where `Name` is the argument name and `Value` is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose `Name` in quotes.

Example: 'Source','aeroiersdata.mat'

Custom list of Earth orientation data, specified in a MAT-file.

Out-of-range action, specified as a string.

Action to take in case of out-of-range or predicted value dates, specified as a string:

• Warning — Displays warning and indicates that the dates were out-of-range or predicted values.

• Error — Displays error and indicates that the dates were out-of-range or predicted values.

• None — Does not display warning or error.

Data Types: `string`

## Output Arguments

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Movement of the rotation axis with respect to the crust of the Earth, M-by-2 array, in radians.

Error for movement of the rotation axis with respect to the crust of the Earth, specified as an M-by-2 array, in radians.

## Version History

Introduced in R2018b

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