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<h1 id="function-format">Function format <a href="#function-format" title="Permalink">#</a></h1>

Format a value of any type into a string.


<h2 id="syntax">Syntax <a href="#syntax" title="Permalink">#</a></h2>

```js
math.format(value)
math.format(value, options)
math.format(value, precision)
math.format(value, callback)
```

<h3 id="where">Where <a href="#where" title="Permalink">#</a></h3>

 - `value: *`
   The value to be formatted
 - `options: Object`
   An object with formatting options. Available options:
   - `notation: string`
     Number notation. Choose from:
     - `'fixed'`
       Always use regular number notation.
       For example `'123.40'` and `'14000000'`
     - `'exponential'`
       Always use exponential notation.
       For example `'1.234e+2'` and `'1.4e+7'`
     - `'engineering'`
       Always use engineering notation: always have exponential notation,
       and select the exponent to be a multiple of `3`.
       For example `'123.4e+0'` and `'14.0e+6'`
     - `'auto'` (default)
       Regular number notation for numbers having an absolute value between
       `lower` and `upper` bounds, and uses exponential notation elsewhere.
       Lower bound is included, upper bound is excluded.
       For example `'123.4'` and `'1.4e7'`.
     - `'bin'`, `'oct'`, or `'hex'`
       Format the number using binary, octal, or hexadecimal notation.
       For example `'0b1101'` and `'0x10fe'`.
   - `wordSize: number | BigNumber`
     The word size in bits to use for formatting in binary, octal, or
     hexadecimal notation. To be used only with `'bin'`, `'oct'`, or `'hex'`
     values for `notation` option. When this option is defined the value
     is formatted as a signed twos complement integer of the given word
     size and the size suffix is appended to the output.
     For example `format(-1, {notation: 'hex', wordSize: 8}) === '0xffi8'`.
     Default value is undefined.
   - `precision: number | BigNumber`
     Limit the number of digits of the formatted value.
     For regular numbers, must be a number between `0` and `16`.
     For bignumbers, the maximum depends on the configured precision,
     see function `config()`.
     In case of notations `'exponential'`, `'engineering'`, and `'auto'`,
     `precision` defines the total number of significant digits returned.
     In case of notation `'fixed'`, `precision` defines the number of
     significant digits after the decimal point.
     `precision` is undefined by default.
   - `lowerExp: number`
     Exponent determining the lower boundary for formatting a value with
     an exponent when `notation='auto'`. Default value is `-3`.
   - `upperExp: number`
     Exponent determining the upper boundary for formatting a value with
     an exponent when `notation='auto'`. Default value is `5`.
   - `fraction: string`. Available values: `'ratio'` (default) or `'decimal'`.
     For example `format(fraction(1, 3))` will output `'1/3'` when `'ratio'`
     is configured, and will output `'0.(3)'` when `'decimal'` is configured.
   - `truncate: number`. Specifies the maximum allowed length of the
     returned string. If it had been longer, the excess characters
     are deleted and replaced with `'...'`.
- `callback: function`
  A custom formatting function, invoked for all numeric elements in `value`,
  for example all elements of a matrix, or the real and imaginary
  parts of a complex number. This callback can be used to override the
  built-in numeric notation with any type of formatting. Function `callback`
  is called with `value` as parameter and must return a string.

<h3 id="parameters">Parameters <a href="#parameters" title="Permalink">#</a></h3>

Parameter | Type | Description
--------- | ---- | -----------
`value` | * | Value to be stringified
`options` | Object &#124; Function &#124; number | Formatting options

<h3 id="returns">Returns <a href="#returns" title="Permalink">#</a></h3>

Type | Description
---- | -----------
string | The formatted value


<h3 id="throws">Throws <a href="#throws" title="Permalink">#</a></h3>

Type | Description
---- | -----------


<h2 id="examples">Examples <a href="#examples" title="Permalink">#</a></h2>

```js
math.format(6.4)                                        // returns '6.4'
math.format(1240000)                                    // returns '1.24e+6'
math.format(1/3)                                        // returns '0.3333333333333333'
math.format(1/3, 3)                                     // returns '0.333'
math.format(21385, 2)                                   // returns '21000'
math.format(12e8, {notation: 'fixed'})                  // returns '1200000000'
math.format(2.3,  {notation: 'fixed', precision: 4})    // returns '2.3000'
math.format(52.8, {notation: 'exponential'})            // returns '5.28e+1'
math.format(12400, {notation: 'engineering'})           // returns '12.4e+3'
math.format(2000, {lowerExp: -2, upperExp: 2})          // returns '2e+3'

function formatCurrency(value) {
  // return currency notation with two digits:
  return '$' + value.toFixed(2)

  // you could also use math.format inside the callback:
  // return '$' + math.format(value, {notation: 'fixed', precision: 2})
}
math.format([2.1, 3, 0.016], formatCurrency)            // returns '[$2.10, $3.00, $0.02]'
```


<h2 id="see-also">See also <a href="#see-also" title="Permalink">#</a></h2>

[print](print.html)