@stdlib/stats-base-dists-betaprime-ctor NPM

Beta Prime

Beta prime distribution constructor.

Installation

npm install @stdlib/stats-base-dists-betaprime-ctor

Usage

var BetaPrime = require( '@stdlib/stats-base-dists-betaprime-ctor' );

BetaPrime( [alpha, beta] )

Returns a beta prime distribution object.

var betaprime = new BetaPrime();

var mode = betaprime.mode;
// returns 0.0

By default, alpha = 1.0 and beta = 1.0. To create a distribution having a different alpha (first shape parameter) and beta (second shape parameter), provide the corresponding arguments.

var betaprime = new BetaPrime( 2.0, 4.0 );

var mu = betaprime.mean;
// returns ~0.667

betaprime

A beta prime distribution object has the following properties and methods...

Writable Properties

betaprime.alpha

First shape parameter of the distribution. alpha must be a positive number.

var betaprime = new BetaPrime();

var alpha = betaprime.alpha;
// returns 1.0

betaprime.alpha = 3.0;

alpha = betaprime.alpha;
// returns 3.0

betaprime.beta

Second shape parameter of the distribution. beta must be a positive number.

var betaprime = new BetaPrime( 2.0, 4.0 );

var b = betaprime.beta;
// returns 4.0

betaprime.beta = 3.0;

b = betaprime.beta;
// returns 3.0

Computed Properties

BetaPrime.prototype.kurtosis

Returns the excess kurtosis.

var betaprime = new BetaPrime( 4.0, 12.0 );

var kurtosis = betaprime.kurtosis;
// returns ~5.764

BetaPrime.prototype.mean

Returns the expected value.

var betaprime = new BetaPrime( 4.0, 12.0 );

var mu = betaprime.mean;
// returns ~0.364

BetaPrime.prototype.mode

Returns the mode.

var betaprime = new BetaPrime( 4.0, 12.0 );

var mode = betaprime.mode;
// returns ~0.231

BetaPrime.prototype.skewness

Returns the skewness.

var betaprime = new BetaPrime( 4.0, 12.0 );

var skewness = betaprime.skewness;
// returns ~1.724

BetaPrime.prototype.stdev

Returns the standard deviation.

var betaprime = new BetaPrime( 4.0, 12.0 );

var s = betaprime.stdev;
// returns ~0.223

BetaPrime.prototype.variance

Returns the variance.

var betaprime = new BetaPrime( 4.0, 12.0 );

var s2 = betaprime.variance;
// returns ~0.05

Methods

BetaPrime.prototype.cdf( x )

Evaluates the cumulative distribution function (CDF).

var betaprime = new BetaPrime( 2.0, 4.0 );

var y = betaprime.cdf( 0.5 );
// returns ~0.539

BetaPrime.prototype.logcdf( x )

Evaluates the natural logarithm of the cumulative distribution function (CDF).

var betaprime = new BetaPrime( 2.0, 4.0 );

var y = betaprime.logcdf( 0.5 );
// returns ~-0.618

BetaPrime.prototype.logpdf( x )

Evaluates the natural logarithm of the probability density function (PDF).

var betaprime = new BetaPrime( 2.0, 4.0 );

var y = betaprime.logpdf( 0.8 );
// returns ~-0.754

BetaPrime.prototype.pdf( x )

Evaluates the probability density function (PDF).

var betaprime = new BetaPrime( 2.0, 4.0 );

var y = betaprime.pdf( 0.8 );
// returns ~0.47

BetaPrime.prototype.quantile( p )

Evaluates the quantile function at probability p.

var betaprime = new BetaPrime( 2.0, 4.0 );

var y = betaprime.quantile( 0.5 );
// returns ~0.457

y = betaprime.quantile( 1.9 );
// returns NaN

Examples

var BetaPrime = require( '@stdlib/stats-base-dists-betaprime-ctor' );

var betaprime = new BetaPrime( 2.0, 4.0 );

var mu = betaprime.mean;
// returns ~0.667

var mode = betaprime.mode;
// returns 0.2

var s2 = betaprime.variance;
// returns ~0.556

var y = betaprime.cdf( 0.8 );
// returns ~0.735

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.