MathPHP\Probability\Distribution\Continuous\Weibull Class Reference

Inheritance diagram for MathPHP\Probability\Distribution\Continuous\Weibull:

Collaboration diagram for MathPHP\Probability\Distribution\Continuous\Weibull:

Public Member Functions
	__construct (float $k, float $λ)
	Constructor. More...
	pdf (float $x)
	Weibull distribution - probability density function. More...
	cdf (float $x)
	Weibull distribution - cumulative distribution function From 0 to x (lower CDF) https://en.wikipedia.org/wiki/Weibull_distribution. More...
	inverse (float $p)
	Inverse CDF (Quantile function) More...
	mean ()
	Mean of the distribution. More...
	median ()
	Median of the distribution. More...
	mode ()
	Mode of the distribution. More...
Public Member Functions inherited from MathPHP\Probability\Distribution\Continuous\Continuous
	inverse (float $target)
	The Inverse CDF of the distribution. More...
	between (float $x₁, float $x₂)
	CDF between - probability of being between two points, x₁ and x₂ The area under a continuous distribution, that lies between two specified points. More...
	outside (float $x₁, float $x₂)
	CDF outside - Probability of being below x₁ and above x₂. More...
	above (float $x)
	CDF above - Probability of being above x to ∞ Area under a continuous distribution, that lies above a specified point. More...
	rand ()
	Produce a random number with a particular distribution. More...
Public Member Functions inherited from MathPHP\Probability\Distribution\Distribution
	__construct (... $params)
	Constructor. More...

Public Attributes
const	PARAMETER_LIMITS
const	SUPPORT_LIMITS
Public Attributes inherited from MathPHP\Probability\Distribution\Continuous\Continuous
const	GUESS_THRESHOLD = 10
const	GUESS_ALLOWANCE = 8

Protected Attributes
	$k
	$λ

Constructor & Destructor Documentation

__construct()

MathPHP\Probability\Distribution\Continuous\Weibull::__construct	(	float	$k,
		float	$λ
	)

Constructor.

Parameters

float	$k	shape parameter k > 0
float	$λ	scale parameter λ > 0

Member Function Documentation

cdf()

MathPHP\Probability\Distribution\Continuous\Weibull::cdf

(

float

$x

)

Weibull distribution - cumulative distribution function From 0 to x (lower CDF) https://en.wikipedia.org/wiki/Weibull_distribution.

f(x) = 1 - ℯ⁻⁽x/λ⁾ for x ≥ 0 f(x) = 0 for x < 0

Parameters

float

$x

percentile (value to evaluate)

Returns

float

Implements MathPHP\Probability\Distribution\Continuous\ContinuousDistribution.

inverse()

MathPHP\Probability\Distribution\Continuous\Weibull::inverse

(

float

$p

)

Inverse CDF (Quantile function)

Q(p;k,λ) = λ(-ln(1 - p))¹/ᵏ

Parameters

float

$p

Returns

float

mean()

MathPHP\Probability\Distribution\Continuous\Weibull::mean

(

)

Mean of the distribution.

μ = λΓ(1 + 1/k)

Returns

float

Implements MathPHP\Probability\Distribution\Continuous\ContinuousDistribution.

median()

MathPHP\Probability\Distribution\Continuous\Weibull::median

(

)

Median of the distribution.

median = λ(ln 2)¹ᐟᵏ

Returns

float

mode()

MathPHP\Probability\Distribution\Continuous\Weibull::mode

(

)

Mode of the distribution.

/ k - 1 \¹ᐟᵏ λ | --— | \ k /

0 k ≤ 1

Returns

float

pdf()

MathPHP\Probability\Distribution\Continuous\Weibull::pdf

(

float

$x

)

Weibull distribution - probability density function.

https://en.wikipedia.org/wiki/Weibull_distribution

   k  /x\ ᵏ⁻¹        ᵏ

f(x) = - | - | ℯ⁻⁽x/λ⁾ for x ≥ 0 λ \λ/

f(x) = 0 for x < 0

Parameters

float

$x

percentile (value to evaluate)

Returns

float

Implements MathPHP\Probability\Distribution\Continuous\ContinuousDistribution.

Member Data Documentation

PARAMETER_LIMITS

const MathPHP\Probability\Distribution\Continuous\Weibull::PARAMETER_LIMITS

Initial value:

= [
        'k' => '(0,∞)'

SUPPORT_LIMITS

const MathPHP\Probability\Distribution\Continuous\Weibull::SUPPORT_LIMITS

Initial value:

= [
        'x' => '(-∞,∞)'

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The documentation for this class was generated from the following file:

• src/Probability/Distribution/Continuous/Weibull.php