mathjs/docs/reference/functions/format.md

Function format

Format a value of any type into a string.

Syntax

math.format(value)
math.format(value, options)
math.format(value, precision)
math.format(value, fn)

Where

• 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'
    • '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'.
  • precision: number A number between 0 and 16 to round the digits of the number. In case of notations 'exponential' and 'auto', precision defines the total number of significant digits returned and is undefined by default. In case of notation 'fixed', precision defines the number of significant digits after the decimal point, and is 0 by default.
  • exponential: Object An object containing two parameters, {number} lower and {number} upper, used by notation 'auto' to determine when to return exponential notation. Default values are lower=1e-3 and upper=1e5. Only applicable for notation auto.
  • 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.
• fn: Function A custom formatting function. Can be used to override the built-in notations. Function fn is called with value as parameter and must return a string. Is useful for example to format all values inside a matrix in a particular way.

Parameters

Parameter	Type	Description
value	*	Value to be stringified
options	Object | Function | number	Formatting options

Returns

Type	Description
string	The formatted value

Examples

math.format(6.4);                                        // returns '6.4'
math.format(1240000);                                    // returns '1.24e6'
math.format(1/3);                                        // returns '0.3333333333333333'
math.format(1/3, 3);                                     // returns '0.333'
math.format(21385, 2);                                   // returns '21000'
math.format(12.071, {notation: 'fixed'});                // returns '12'
math.format(2.3,    {notation: 'fixed', precision: 2});  // returns '2.30'
math.format(52.8,   {notation: 'exponential'});          // returns '5.28e+1'

See also

print