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AdvancedMath

Package | com.masterbaboon
Class | public class AdvancedMath
Inheritance | AdvancedMath Object

Collection of advanced math functions for AS3

Public Methods

| Method | Defined By
--- | --- | ---
|  | add(x:Array, y:Array):Array [static] Add two arrays elementwise. | AdvancedMath
|  | factorial(x:int):Number [static] Computes the factorial of x. | AdvancedMath
|  | gamma(x:Number):Number [static] Lanczos implementation of the Gamma function, cf. | AdvancedMath
|  | lnGamma(x:Number):Number [static] Lanczos implementation of the log Gamma function, cf. | AdvancedMath
|  | mean(x:Array):Number [static] Compute the mean of the input array x. | AdvancedMath
|  | sampleDirichlet(alpha:Array):Array [static] Sample from a Dirichlet distribution. | AdvancedMath
|  | sampleGamma(k:Number, theta:Number):Number [static] Sample from a Gamma(k, theta) distribution. | AdvancedMath
|  | sampleMultinomial(p:Array):int [static] Sample from a multinomial distribution. | AdvancedMath
|  | sum(x:Array):Number [static] Compute the sum of the elements of the input array x | AdvancedMath
|  | variance(x:Array):Number [static] Compute the variance of the input array x. | AdvancedMath
|  | zeros(dim:int, val:Number = 0):Array [static] Create a new array with elements initialized to a particular value. | AdvancedMath

Public Constants

| Constant | Defined By
--- | --- | ---
|  | FACTORIAL_MAXEXACT : Number = 20 [static] | AdvancedMath

Method Detail

add | () | method

`public static function add(x:Array, y:Array):Array`

Add two arrays elementwise. They must be of the same length.

Parameters

| `x:Array`
| `y:Array`

Returns

| `Array`

factorial | () | method |

`public static function factorial(x:int):Number`

Computes the factorial of x. Requested values are cached to speed-up future calls. If x>FACTORIAL_MAXEXACT, the result is approximated using the Gamma function, as x! = Gamma(x+1) .

Parameters

| `x:int`

Returns

| `Number`

gamma | () | method |

`public static function gamma(x:Number):Number`

Lanczos implementation of the Gamma function, cf. Numerical Recipes in C (2nd edition, p.213). Reference: Lanczos, C. 1964, SIAM Journal on Numerical Analysis, ser. B, vol. 1, pp. 86–96.

Parameters

| `x:Number`

Returns

| `Number`

lnGamma | () | method |

`public static function lnGamma(x:Number):Number`

Lanczos implementation of the log Gamma function, cf. Numerical Recipes in C (2nd edition, p.213). Reference: Lanczos, C. 1964, SIAM Journal on Numerical Analysis, ser. B, vol. 1, pp. 86–96.

Parameters

| `x:Number`

Returns

| `Number`

mean | () | method |

`public static function mean(x:Array):Number`

Compute the mean of the input array x.

Parameters

| `x:Array`

Returns

| `Number`

sampleDirichlet | () | method |

`public static function sampleDirichlet(alpha:Array):Array`

Sample from a Dirichlet distribution. Dirichlet distribution can be used as prior for multinomial variables.

Parameters

| `alpha:Array` — Array of parameters for the Dirichlet distribution

Returns

| `Array`

See also

sampleDirichlet2

sampleGamma | () | method |

`public static function sampleGamma(k:Number, theta:Number):Number`

Sample from a Gamma(k, theta) distribution. The definition and the sample generating algorithm are as at http://en.wikipedia.org/wiki/Gamma_distribution . For the Matlab Gamma(alpha, beta) definition, call Gamma(alpha, 1/beta).

Parameters

| `k:Number`
| `theta:Number`

Returns

| `Number`

sampleMultinomial | () | method |

`public static function sampleMultinomial(p:Array):int`

Sample from a multinomial distribution. In other words, choose randomly from a set of N choices with probabilities p[0], ..., p[N-1]

Parameters

| `p:Array` — An array of probabilities, one for each element. p must sum to 1.

Returns

| `int`

sum | () | method |

`public static function sum(x:Array):Number`

Compute the sum of the elements of the input array x

Parameters

| `x:Array`

Returns

| `Number`

variance | () | method |

`public static function variance(x:Array):Number`

Compute the variance of the input array x.

Parameters

| `x:Array`

Returns

| `Number`

zeros | () | method |

`public static function zeros(dim:int, val:Number = 0):Array`

Create a new array with elements initialized to a particular value.

Parameters

| `dim:int` — Number of dimensions
| `val:Number` (default = `0`)`` — Value to initialize the array to. Default: 0

Returns

| `Array`

Constant Detail

FACTORIAL_MAXEXACT | Constant

`public static const FACTORIAL_MAXEXACT:Number = 20`

Thu Jan 16 2014, 01:11 PM +08:00