# separateUnits

Separate units from expression

## Description

example

[Data,Units] = separateUnits(expr) returns the symbolic units of the symbolic expression expr in Units and the rest of expr in Data.

example

Data = separateUnits(expr) removes symbolic units from expr and then returns the rest.

## Examples

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Separate the units from the expression 10*t*u.m/u.s, where u = symunit, by providing two output arguments for separateUnits.

u = symunit;
syms t
speed = 10*t*u.m/u.s;
[Data,Units] = separateUnits(speed)
Data = $10 t$
Units =

$\frac{\mathrm{m}\mathrm{"meter - a physical unit of length."}}{\mathrm{s}\mathrm{"second - a physical unit of time."}}$

Return only the expression with the units removed by providing one output argument.

Data = separateUnits(speed)
Data = $10 t$

If the input has compatible units that can be converted to the same unit, then separateUnits performs the conversion and returns the separated result. Units are compatible when they have the same dimensions (although the conversion factor may not necessarily be 1).

Separate the units from 2*u.m + 30*u.cm + 12*u.in. Even though the units differ, separateUnits converts them to the same unit and returns the separated result.

u = symunit;
[Data,Units] = separateUnits(2*u.m + 30*u.cm + 12*u.in)
Data =

$\frac{1628}{625}$

Units = $\mathrm{m}\mathrm{"meter - a physical unit of length."}$

## Input Arguments

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Input, specified as a number, vector, matrix, or multidimensional array, or a symbolic number, variable, vector, matrix, equation, multidimensional array, function, or expression.

When adding or subtracting quantities with different units in expr, the units must be compatible. Units are compatible when they have the same dimensions. For example, see Separate Compatible Units.

## Output Arguments

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Expression after removing units, returned as a number, vector, matrix, or multidimensional array, or a symbolic number, variable, vector, matrix, equation, multidimensional array, function, or expression.

Units from input, returned as symbolic units.

## Tips

• If an expression has incompatible units, then separateUnits errors. Units are incompatible when they do not have the same dimensions, such as length and time.

For example, this code will error.

u = symunit;
[Data,Units] = separateUnits(2*u.m + 3*u.s)

Instead, to return the units in the input, use findUnits.

Units = findUnits(2*u.m + 3*u.s)
Units =
[[m], [s]]

## Version History

Introduced in R2017a

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