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

Kurtosis

Beta prime distribution excess kurtosis.

The excess kurtosis for a beta prime random variable with first shape parameter α and second shape parameter β is

when α > 0 and β > 4. Otherwise, the excess kurtosis is not defined.

Installation

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

Usage

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

kurtosis( alpha, beta )

Returns the excess kurtosis of a beta prime distribution with parameters alpha (first shape parameter) and beta (second shape parameter).

var v = kurtosis( 2.0, 5.0 );
// returns 54.0

v = kurtosis( 4.0, 12.0 );
// returns ~5.764

v = kurtosis( 12.0, 6.0 );
// returns ~19.49

If provided NaN as any argument, the function returns NaN.

var v = kurtosis( NaN, 5.0 );
// returns NaN

v = kurtosis( 2.0, NaN );
// returns NaN

If provided alpha <= 0, the function returns NaN.

var v = kurtosis( 0.0, 5.0 );
// returns NaN

v = kurtosis( -1.0, 5.0 );
// returns NaN

If provided beta <= 4, the function returns NaN.

var v = kurtosis( 1.0, 3.5 );
// returns NaN

v = kurtosis( 1.0, 2.0 );
// returns NaN

v = kurtosis( 1.0, -1.0 );
// returns NaN

Examples

var randu = require( '@stdlib/random-base-randu' );
var EPS = require( '@stdlib/constants-float64-eps' );
var kurtosis = require( '@stdlib/stats-base-dists-betaprime-kurtosis' );

var alpha;
var beta;
var v;
var i;

for ( i = 0; i < 10; i++ ) {
    alpha = ( randu()*10.0 ) + EPS;
    beta = ( randu()*10.0 ) + 4.0 + EPS;
    v = kurtosis( alpha, beta );
    console.log( 'α: %d, β: %d, Kurt(X;α,β): %d', alpha.toFixed( 4 ), beta.toFixed( 4 ), v.toFixed( 4 ) );
}

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.