Core JavaScript 1.5 Reference:Global Objects:Math

From MDC

Contents 1 Summary 2 Description 3 Properties 4 Methods

[edit] Summary

A built-in object that has properties and methods for mathematical constants and functions.

[edit] Description

Unlike the other global objects, Math is not a constructor. All properties and methods of Math are static. You refer to the constant pi as Math.PI and you call the sine function as Math.sin(x), where x is the method's argument. Constants are defined with the full precision of real numbers in JavaScript.

It is often convenient to use the with statement when a section of code uses several Math constants and methods, so you don't have to type "Math" repeatedly. For example,

with (Math) {
   a = PI * r*r;
   y = r*sin(theta);
   x = r*cos(theta);
}

[edit] Properties

E

Euler's constant and the base of natural logarithms, approximately 2.718.

LN2

Natural logarithm of 2, approximately 0.693.

LN10

Natural logarithm of 10, approximately 2.302.

LOG2E

Base 2 logarithm of E, approximately 1.442.

LOG10E

Base 10 logarithm of E, approximately 0.434.

PI

Ratio of the circumference of a circle to its diameter, approximately 3.14159.

SQRT1_2

Square root of 1/2; equivalently, 1 over the square root of 2, approximately 0.707.

SQRT2

Square root of 2, approximately 1.414.

[edit] Methods

abs

Returns the absolute value of a number.

acos

Returns the arccosine (in radians) of a number.

asin

Returns the arcsine (in radians) of a number.

atan

Returns the arctangent (in radians) of a number.

atan2

Returns the arctangent of the quotient of its arguments.

ceil

Returns the smallest integer greater than or equal to a number.

cos

Returns the cosine of a number.

exp

Returns E^number, where number is the argument, and E is Euler's constant, the base of the natural logarithm.

floor

Returns the largest integer less than or equal to a number.

log

Returns the natural logarithm (base E) of a number.

max

Returns the largest of zero or more numbers.

min

Returns the smallest of zero or more numbers.

pow

Returns base to the exponent power, that is, base exponent.

random

Returns a pseudo-random number between 0 and 1.

round

Returns the value of a number rounded to the nearest integer.

sin

Returns the sine of a number.

sqrt

Returns the square root of a number.

tan

Returns the tangent of a number.

toSource

Non-standard

Returns the string "Math".