@stdlib/stats-base-dists-weibull-median NPM

Median

Weibull distribution median.

The median for a Weibull random variable is

where lambda > 0 is the shape parameter and k > 0 is the scale parameter.

Installation

npm install @stdlib/stats-base-dists-weibull-median

Usage

var median = require( '@stdlib/stats-base-dists-weibull-median' );

median( k, lambda )

Returns the median of a Weibull distribution with parameters k (shape parameter) and lambda (scale parameter).

var v = median( 1.0, 1.0 );
// returns ~0.693

v = median( 4.0, 12.0 );
// returns ~10.949

v = median( 8.0, 2.0 );
// returns ~1.91

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

var v = median( NaN, 2.0 );
// returns NaN

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

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

var v = median( 0.0, 1.0 );
// returns NaN

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

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

var v = median( 1.0, 0.0 );
// returns NaN

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

Examples

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

var lambda;
var k;
var v;
var i;

for ( i = 0; i < 10; i++ ) {
    k = ( randu()*10.0 ) + EPS;
    lambda = ( randu()*10.0 ) + EPS;
    v = median( k, lambda );
    console.log( 'k: %d, λ: %d, Median(X;k,λ): %d', k.toFixed( 4 ), lambda.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.