Speaking JavaScript

Chapter 21. Math

The Math object is used as a namespace for several math functions. This chapter provides an overview.

Math Properties

The properties of Math are as follows:

Math.E

Euler’s constant (e)

Math.LN2

Natural logarithm of 2

Math.LN10

Natural logarithm of 10

Math.LOG2E

Base 2 logarithm of e

Math.LOG10E

Base 10 logarithm of e

Math.PI

The ratio of the circumference of a circle to its diameter (3.14159 ...), π

Math.SQRT1_2

The square root of one-half,

Math.SQRT2

The square root of two,

Numerical Functions

The numerical functions of Math include the following:

Math.abs(x)

Returns the absolute value of x.

Math.ceil(x)

Returns the smallest integer ≥ x:

> Math.ceil(3.999)
4
> Math.ceil(3.001)
4
> Math.ceil(-3.001)
-3
> Math.ceil(3.000)
3

For more on converting floating-point numbers to integers, see Converting to Integer.

Math.exp(x)

Returns e^x where e is Euler’s constant (Math.E). This is the inverse of Math.log().

Math.floor(x)

Returns the largest integer ≤ x:

> Math.floor(3.999)
3
> Math.floor(3.001)
3
> Math.floor(-3.001)
-4
> Math.floor(3.000)
3

For more on converting floating-point numbers to integers, see Converting to Integer.

Math.log(x)

Returns the natural (base is Euler’s constant) logarithm ln(x) of x. This is the inverse of Math.exp().

Math.pow(x, ...