mathjs/docs/reference/functions/setMultiplicity.md

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

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# Function setMultiplicity

Count the multiplicity of an element in a multiset.
A multi-dimension array will be converted to a single-dimension array before the operation.


## Syntax

```js
math.setMultiplicity(element, set)
```

### Parameters

Parameter | Type | Description
--------- | ---- | -----------
`e` | number &#124; BigNumber &#124; Fraction &#124; Complex | An element in the multiset
`a` | Array &#124; Matrix | A multiset

### Returns

Type | Description
---- | -----------
number | The number of how many times the multiset contains the element


## Examples

```js
math.setMultiplicity(1, [1, 2, 2, 4])    // returns 1
math.setMultiplicity(2, [1, 2, 2, 4])    // returns 2
```


## See also

[setDistinct](setDistinct.md),
[setSize](setSize.md)