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The Math.expm1() function returns ex - 1, where x is the argument, and e the base of the natural logarithms.

Syntax

Math.expm1(x)

Parameters

x
A number.

Return value

A number representing ex - 1, where e is Euler's number and x is the argument.

Description

Because expm1() is a static method of Math, you always use it as Math.expm1(), rather than as a method of a Math object you created (Math is not a constructor).

Examples

Using Math.expm1()

Math.expm1(-1); // -0.6321205588285577 
Math.expm1(0);  // 0
Math.expm1(1);  // 1.718281828459045

Polyfill

This can be emulated with the help of the Math.exp() function:

Math.expm1 = Math.expm1 || function(x) {
  return Math.exp(x) - 1;
};

Specifications

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.expm1' in that specification.
Standard Initial definition.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Math.expm1' in that specification.
Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 38 25 (25) No support 25 7.1
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support No support 25.0 (25) No support No support 8

See also

Document Tags and Contributors

 Contributors to this page: eduardoboucas, fscholz, Mingun, realityking, SphinxKnight, fred.wang
 Last updated by: eduardoboucas,