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A built-in object that has properties and methods for mathematical constants and functions. For example, the Math object's PI property has the value of pi.
The Math object is a top-level, predefined JavaScript object. You can automatically access it without using a constructor or calling a method.
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)
}
In addition, this object inherits the watch and unwatch methods from Object.
Returns the absolute value of a number.
abs(x)
The following function returns the absolute value of the variable x:
function getAbs(x) {
return Math.abs(x)
}
Because abs is a static method of Math, you always use it as Math.abs(), rather than as a method of a Math object you created.
Returns the arccosine (in radians) of a number.
acos(x)
The acos method returns a numeric value between 0 and pi radians. If the value of number is outside this range, it returns NaN.
Because acos is a static method of Math, you always use it as Math.acos(), rather than as a method of a Math object you created.
The following function returns the arccosine of the variable x:
function getAcos(x) {
return Math.acos(x)
}
If you pass -1 to getAcos, it returns 3.141592653589793; if you pass 2, it returns NaN because 2 is out of range.
Math.asin, Math.atan, Math.atan2, Math.cos, Math.sin, Math.tan
Returns the arcsine (in radians) of a number.
asin(x)
The asin method returns a numeric value between -pi/2 and pi/2 radians. If the value of number is outside this range, it returns NaN.
Because asin is a static method of Math, you always use it as Math.asin(), rather than as a method of a Math object you created.
The following function returns the arcsine of the variable x:
function getAsin(x) {
return Math.asin(x)
}
If you pass getAsin the value 1, it returns 1.570796326794897 (pi/2); if you pass it the value 2, it returns NaN because 2 is out of range.
Math.acos, Math.atan, Math.atan2, Math.cos, Math.sin, Math.tan
Returns the arctangent (in radians) of a number.
atan(x)
The atan method returns a numeric value between -pi/2 and pi/2 radians.
Because atan is a static method of Math, you always use it as Math.atan(), rather than as a method of a Math object you created.
The following function returns the arctangent of the variable x:
function getAtan(x) {
return Math.atan(x)
}
If you pass getAtan the value 1, it returns 0.7853981633974483; if you pass it the value .5, it returns 0.4636476090008061.
Math.acos, Math.asin, Math.atan2, Math.cos, Math.sin, Math.tan
Returns the arctangent of the quotient of its arguments.
atan2(y, x)
The atan2 method returns a numeric value between -pi and pi representing the angle theta of an (x,y) point. This is the counterclockwise angle, measured in radians, between the positive X axis, and the point (x,y). Note that the arguments to this function pass the y-coordinate first and the x-coordinate second.
atan2 is passed separate x and y arguments, and atan is passed the ratio of those two arguments.
Because atan2 is a static method of Math, you always use it as Math.atan2(), rather than as a method of a Math object you created.
The following function returns the angle of the polar coordinate:
function getAtan2(x,y) {
return Math.atan2(x,y)
}
If you pass getAtan2 the values (90,15), it returns 1.4056476493802699; if you pass it the values (15,90), it returns 0.16514867741462683.
Math.acos, Math.asin, Math.atan, Math.cos, Math.sin, Math.tan
Returns the smallest integer greater than or equal to a number.
ceil(x)
Because ceil is a static method of Math, you always use it as Math.ceil(), rather than as a method of a Math object you created.
The following function returns the ceil value of the variable x:
function getCeil(x) {
return Math.ceil(x)
}
If you pass 45.95 to getCeil, it returns 46; if you pass -45.95, it returns -45.
Math.floor
Returns the cosine of a number.
cos(x)
The cos method returns a numeric value between -1 and 1, which represents the cosine of the angle.
Because cos is a static method of Math, you always use it as Math.cos(), rather than as a method of a Math object you created.
The following function returns the cosine of the variable x:
function getCos(x) {
return Math.cos(x)
}
If x equals 2*Math.PI, getCos returns 1; if x equals Math.PI, the getCos method returns -1.
Math.acos, Math.asin, Math.atan, Math.atan2, Math.sin, Math.tan
Euler's constant and the base of natural logarithms, approximately 2.718.
Because E is a static property of Math, you always use it as Math.E, rather than as a property of a Math object you created.
The following function returns Euler's constant:
function getEuler() {
return Math.E
}
Returns Ex, where x is the argument, and E is Euler's constant, the base of the natural logarithms.
exp(x)
Because exp is a static method of Math, you always use it as Math.exp(), rather than as a method of a Math object you created.
The following function returns the exponential value of the variable x:
function getExp(x) {
return Math.exp(x)
}
If you pass getExp the value 1, it returns 2.718281828459045.
Math.E, Math.log, Math.pow
Returns the largest integer less than or equal to a number.
floor(x)
Because floor is a static method of Math, you always use it as Math.floor(), rather than as a method of a Math object you created.
The following function returns the floor value of the variable x:
function getFloor(x) {
return Math.floor(x)
}
If you pass 45.95 to getFloor, it returns 45; if you pass -45.95, it returns -46.
Math.ceil
The natural logarithm of 10, approximately 2.302.
The following function returns the natural log of 10:
function getNatLog10() {
return Math.LN10
}
Because LN10 is a static property of Math, you always use it as Math.LN10, rather than as a property of a Math object you created.
The natural logarithm of 2, approximately 0.693.
The following function returns the natural log of 2:
function getNatLog2() {
return Math.LN2
}
Because LN2 is a static property of Math, you always use it as Math.LN2, rather than as a property of a Math object you created.
Returns the natural logarithm (base E) of a number.
log(x)
If the value of number is negative, the return value is always NaN.
Because log is a static method of Math, you always use it as Math.log(), rather than as a method of a Math object you created.
The following function returns the natural log of the variable x:
function getLog(x) {
return Math.log(x)
}
If you pass getLog the value 10, it returns 2.302585092994046; if you pass it the value 0, it returns -Infinity; if you pass it the value -1, it returns NaN because -1 is out of range.
Math.exp, Math.pow
The base 10 logarithm of E (approximately 0.434).
The following function returns the base 10 logarithm of E:
function getLog10e() {
return Math.LOG10E
}
Because LOG10E is a static property of Math, you always use it as Math.LOG10E, rather than as a property of a Math object you created.
The base 2 logarithm of E (approximately 1.442).
The following function returns the base 2 logarithm of E:
function getLog2e() {
return Math.LOG2E
}
Because LOG2E is a static property of Math, you always use it as Math.LOG2E, rather than as a property of a Math object you created.
Returns the larger of two numbers.
max(x,y)
Because max is a static method of Math, you always use it as Math.max(), rather than as a method of a Math object you created.
The following function evaluates the variables x and y:
function getMax(x,y) {
return Math.max(x,y)
}
If you pass getMax the values 10 and 20, it returns 20; if you pass it the values -10 and -20, it returns -10.
Math.min
Returns the smaller of two numbers.
min(x,y)
Because min is a static method of Math, you always use it as Math.min(), rather than as a method of a Math object you created.
The following function evaluates the variables x and y:
function getMin(x,y) {
return Math.min(x,y)
}
If you pass getMin the values 10 and 20, it returns 10; if you pass it the values -10 and -20, it returns -20.
Math.max
The ratio of the circumference of a circle to its diameter, approximately 3.14159.
The following function returns the value of pi:
function getPi() {
return Math.PI
}
Because PI is a static property of Math, you always use it as Math.PI, rather than as a property of a Math object you created.
Returns base to the exponent power, that is, baseexponent.
pow(x,y)
Because pow is a static method of Math, you always use it as Math.pow(), rather than as a method of a Math object you created.
function raisePower(x,y) {
return Math.pow(x,y)
}
If x is 7 and y is 2, raisePower returns 49 (7 to the power of 2).
Math.exp, Math.log
Returns a pseudo-random number between 0 and 1. The random number generator is seeded from the current time, as in Java.
random()
None.
Because random is a static method of Math, you always use it as Math.random(), rather than as a method of a Math object you created.
//Returns a random number between 0 and 1
function getRandom() {
return Math.random()
}
Returns the value of a number rounded to the nearest integer.
round(x)
If the fractional portion of number is .5 or greater, the argument is rounded to the next higher integer. If the fractional portion of number is less than .5, the argument is rounded to the next lower integer.
Because round is a static method of Math, you always use it as Math.round(), rather than as a method of a Math object you created.
//Returns the value 20
x=Math.round(20.49)
//Returns the value 21
x=Math.round(20.5)
//Returns the value -20
x=Math.round(-20.5)
//Returns the value -21
x=Math.round(-20.51)
Returns the sine of a number.
sin(x)
The sin method returns a numeric value between -1 and 1, which represents the sine of the argument.
Because sin is a static method of Math, you always use it as Math.sin(), rather than as a method of a Math object you created.
The following function returns the sine of the variable x:
function getSine(x) {
return Math.sin(x)
}
If you pass getSine the value Math.PI/2, it returns 1.
Math.acos, Math.asin, Math.atan, Math.atan2, Math.cos, Math.tan
Returns the square root of a number.
sqrt(x)
If the value of number is negative, sqrt returns NaN.
Because sqrt is a static method of Math, you always use it as Math.sqrt(), rather than as a method of a Math object you created.
The following function returns the square root of the variable x:
function getRoot(x) {
return Math.sqrt(x)
}
If you pass getRoot the value 9, it returns 3; if you pass it the value 2, it returns 1.414213562373095.
The square root of 1/2; equivalently, 1 over the square root of 2, approximately 0.707.
The following function returns 1 over the square root of 2:
function getRoot1_2() {
return Math.SQRT1_2
}
Because SQRT1_2 is a static property of Math, you always use it as Math.SQRT1_2, rather than as a property of a Math object you created.
The square root of 2, approximately 1.414.
The following function returns the square root of 2:
function getRoot2() {
return Math.SQRT2
}
Because SQRT2 is a static property of Math, you always use it as Math.SQRT2, rather than as a property of a Math object you created.
Returns the tangent of a number.
tan(x)
The tan method returns a numeric value that represents the tangent of the angle.
Because tan is a static method of Math, you always use it as Math.tan(), rather than as a method of a Math object you created.
The following function returns the tangent of the variable x:
function getTan(x) {
return Math.tan(x)
}
Math.acos, Math.asin, Math.atan, Math.atan2, Math.cos, Math.sin
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Last Updated: 11/13/98 10:23:24
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