All of the maths functions in JavaScript are kept in a handy object called **Math**, which contains a number of different functions.

To get the absolute value of a number use the abs() function.

`Math.abs(3.14159265) // returns 3.14159265`

Rounding a number is done by either the round() function to round to the nearest integer, the ceil() function to round up to the nearest integer and the floor() function to round down to the nearest integer.

Math.ceil(3.14159265) // returns 4 Math.floor(3.14159265) // returns 3 Math.round(3.14159265) // returns 3

To find the exponent of a number use the exp() function.

`Math.exp(3.14159265) // returns 23.140692549708973`

The log() method returns the natural logarithm (base E) of a number.

`Math.log(3.14159265) // returns 1.1447298847067335`

Raising a number by a value is done with the pow() function, the two parameters are the number and the power.

`Math.pow(3.14159265) // returns 4.114463202429791`

Finding the square root of a number is done by using the sqrt() function.

`Math.sqrt(3.14159265) // returns 1.7724538498928541`

A pseudo random number between 0 and 1 can be found by using the random() function.

`Math.random() // returns a number between 0 and 1`

A group of trigonometric functions also exist.

Math.tan(1.5707963267948966) // returns 16331778728383844 Math.cos(1.5707963267948966) // returns 6.123031769111886e-17 Math.sin(1.5707963267948966) // returns 1 Math.atan(1.5707963267948966) // returns 1.0038848218538872 Math.atan2(1.5707963267948966,1.23567) // arc tangent of a/b - returns 0.9042475963309642 Math.acos(0.5) // returns 1.0471975511965976 Math.asin(0.5) // returns 0.5235987755982989

All of the trigonometric functions work with radians and not degrees so you will need to convert degrees to radians if that is what you are working in. To convert radians to degrees multiply the value by PI divided by 180. To convert degrees to radians multiply the value by 180 divided by PI.

// degrees to radians var rad = (90*(Math.PI/180)); // returns 1.5707963267948966 // radians to degrees var deg = (1.5707963267948966*(180/Math.PI)); // returns 90

To compare numbers you can use the min() and max() functions. The min() function will return the smallest number from a set of values and max() will returns the largest number from a set of values.

Math.max(1,2,3,4,5,6,7,8,9) // returns 9 Math.min(1,2,3,4,5,6,7,8,9) // returns 1

Additionally, there are a few constant values available in the Math object, these are as follows.

**Math.E**- Euler's constant (also known as e) = 2.718281828459045**Math.LN2**- Natural log of the value 2 = 0.6931471805599453**Math.LN10**- Natural log of the value 10 = 2.302585092994046**Math.LOG2E**- The base 2 log of e = 2.302585092994046**Math.LOG10E**- The base 10 log of e = 0.4342944819032518**Math.PI**- Pi = 3.141592653589793**Math.SQRT1_2**- The square root of one half = 0.7071067811865476**Math.SQRT2**- The square root of 2 = 1.4142135623730951

There are also some constants kept in the Number object. These are mainly used to validate integers and are as follows.

**Number.MAX_VALUE**- The largest value of an integer that can be used in JavaScript. This value is 1.7976931348623157e+308**Number.MIN_VALUE**- The smallest value of an integer that can be used in JavaScript. This value is 5e-324.**Number.NaN**- Used to indicate that a value is not a number.**Number.NEGATIVE_INFINITY**- The value returned if a negative overflow occurs. Any numeric value divided by this is 0.**Number.POSITIVE_INFINITY**- The value returned if a positive value overflow occurs. Any numeric value divided by this is 0.

All of these constants can be used as validation. For example, trying to run a function with an integer that is above the maximum limit can cause errors, so a simple checksum can be put in place.

if (value1*value2 <= Number.MAX_VALUE) { function1(value1) } else { function2(value1) }

## Comments

PI 3.141592653589793 - firefox 2.0 PI 3.141592653589793 - opera 9.2 PI 3.141592653589793 - IE 7