OBJECT:
Math
The
Math object is a top-level, built-in JavaScript object which can
be accessed without using a constructor or calling a method. It also has
static properties and methods for mathematical constants and functions.
This means that you can refer to, say, the constant PI as Math.PI,
and you can call the Tangent function with Math.tan(x). To illustrate
this, the following code calculates the length of the side of a right-angled
triangle opposite the angle Theta:
Code:
len = Math.tan(theta) * adj
All constants are defined as precision real numbers in JavaScript.
When using several Math constants and methods, it is often more convenient
to use the with statement to avoid having to repeatedly type
the word Math:
Code:
with(Math)
{
a = 28.27
adj = sqrt(a/PI)
len = adj * tan(1.1071)
}
PROPERTIES
E Property
This property is Euler's constant and the base of natural logarithms
(approximately 2.7183)
Syntax: Math.E
LN10 Property
This property is the natural logarithm of 10, (approximately 2.3026).
Syntax: Math.LN10
LN2 Property
This property is the natural logarithm of 2, which is approximately
0.6931.
Syntax: Math.LN2
LOG10E Property
This property is the base 10 logarithm of E (approximately 0.4343).
Syntax: Math.LOG10E
LOG2E Property
This property is the base 2 logarithm of E (approximately 1.4427).
Syntax: Math.LOG2E
PI Property
This property is the ratio of the circuference of a circle to its diameter
(approximately 3.1416).
Syntax: Math.PI
SQRT1_2 Property
This property is the value of 1 divided by the square root of 2 and
is approximately equal to 0.7071.
Syntax: Math.SQRT1_2
SQRT2 Property
This property is the square root of 2 (approximately 1.4142).
Syntax: Math.SQRT2
METHODS
abs Method
This method returns the absolute value of a number.
Syntax: Math.abs(x)
acos Method
This method returns the arccosine of a number as a numeric value between
0 and PI radians. Passing it a value for 'x' which is outsite the range
-1 to 1 will cause the Netscape browser to return NaN, and the
Internet Explorer browser to return an error message. Passing it -1
will return the value of PI.
Syntax: Math.acos(x)
asin Method
This method returns the arcsine of a number as a numeric value between
-PI/2 and PI/2 radians. Passing it a value for 'x' which is outsite
the range -1 to 1 will cause the Netscape browser to return NaN,
and the Internet Explorer browser to return an error message. Passing
it 1 will return the value of PI/2.
Syntax: Math.asin(x)
atan Method
This method returns the arctangent of a number as a numeric value between
-PI/2 and PI/2 radians.
Syntax: Math.atan(x)
atan2 Method
This method returns the arctangent of the quotient of its arguments.
Syntax: Math.atan2(y, x)
ceil Method
This method returns an integer equal to, or the next integer greater
than, the number passed to it. Hence, if you passed it 3.79, it would
return 4, and passing it -3.79 would return -3.
Syntax: Math.ceil(x)
cos Method
This method returns the cosine of a number, which will be a numeric
value between -1 and 1.
Syntax: Math.cos(x)
exp Method
This method returns the value of Ex where E is Euler's constant
and x is the argument passed to it.
Syntax: Math.exp(x)
floor Method
This method returns an integer equal to, or the next integer less than,
the number passed to it. Hence, if you passed it 3.79, it would return
3, and passing it -3.79 would return -4.
Syntax: Math.floor(x)
log Method
This method returns the natural logarithm (base E) of a number. If you
pass the log method the number 0, the Netscape browser will return
-Infinity, and with an argument of a negative number NaN. In
both these cases Internet Explorer returns an error message.
Syntax: Math.log(x)
max Method
This method returns the greater of the two numbers passed to it as arguments.
Hence, if you passed it the numbers 9 and 11, it would return 11, whereas
passing it -9 and -11 returns -9.
Syntax: Math.max(x, y)
min Method
This method returns the lesser of the two numbers passed to it as arguments.
Hence, if you passed it the numbers 9 and 11, it would return 9, whereas
passing it -9 and -11 returns -11.
Syntax: Math.min(x, y)
pow Method
This method returns the value of x to the power of y (xy),
where x is the base, and y is the exponent.
Syntax: Math.pow(x, y)
random Method
This method takes no arguments and returns a pseudo-random number between
0 and 1. The random number generator is seeded from the current time.
Syntax: Math.random()
round Method
This method is used to round a number to the nearest integer. If the
fractional portion of the number is .5 or higher, then the number is
rounded up, otherwise it is rounded down.
Syntax: Math.round(x)
sin Method
This method is used to return the sine of its argument, which will be
a number between -1 and 1.
Syntax: Math.sin(x)
sqrt Method
This method returns the square root of a number. If that number is negative,
then the Netscape browser returns the value of NaN, whereas the
Internet Explorer browser returns an Error message.
Syntax: Math.sqrt(x)
tan Method
This method returns a number representing the tangent of an angle.
Syntax: Math.tan(x)
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