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# newUnit

Define new unit

## Syntax

``newUnit(name,definition)``

## Description

example

````newUnit(name,definition)` defines the new unit `name` using the expression `definition`. The definition must be in terms of existing symbolic units. You cannot redefine a predefined unit or its alternate names.```

## Examples

### Define New Unit and Rewrite Unit

Define the new unit `speedOfLight` as `3e8` meters per second.

```u = symunit; c = newUnit('speedOfLight',3e8*u.m/u.s)```
```c = [speedOfLight]```

Define the famous equation E = mc2 using the new unit.

```syms mass m = mass*u.kg; E = m*c^2```
```E = mass*[kg]*[speedOfLight]^2```

Alternatively, you can specify the unit by using `u.SpeedOfLight`.

Rewrite `E` in terms of meters per second.

`E = rewrite(E,u.m/u.s)`
```E = 90000000000000000*mass*(([kg]*[m]^2)/[s]^2)```

Since the standard unit of energy is the Joule, rewrite `E` in terms of `Joule`.

`E = rewrite(E,u.J)`
```E = 90000000000000000*mass*[J]```

## Input Arguments

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Name of the new unit, specified as a character vector or string. You cannot redefine a predefined unit or its aliases.

Definition of the new unit, specified as a symbolic expression of units. The new unit must be defined in terms of existing symbolic units. For example, `newUnit('workday',8*u.hour)` where ```u = symunit```.