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Weibull
Weibull distribution constructor.
Installation
npm install @stdlib/stats-base-dists-weibull-ctor
Usage
var Weibull = require( '@stdlib/stats-base-dists-weibull-ctor' );
Weibull( [k, lambda] )
Returns a Weibull distribution object.
var weibull = new Weibull();
var mode = weibull.mode;
// returns 0.0
By default, k = 1.0
and lambda = 1.0
. To create a distribution having a different k
(shape parameter) and lambda
(scale parameter), provide the corresponding arguments.
var weibull = new Weibull( 2.0, 4.0 );
var mode = weibull.mode;
// returns ~2.828
weibull
A Weibull distribution object has the following properties and methods...
Writable Properties
weibull.k
Shape parameter of the distribution. k
must be a positive number.
var weibull = new Weibull();
var k = weibull.k;
// returns 1.0
weibull.k = 3.0;
k = weibull.k;
// returns 3.0
weibull.lambda
Scale parameter of the distribution. lambda
must be a positive number.
var weibull = new Weibull( 2.0, 4.0 );
var lambda = weibull.lambda;
// returns 4.0
weibull.lambda = 3.0;
lambda = weibull.lambda;
// returns 3.0
Computed Properties
Weibull.prototype.entropy
Returns the differential entropy.
var weibull = new Weibull( 4.0, 12.0 );
var entropy = weibull.entropy;
// returns ~2.532
Weibull.prototype.kurtosis
Returns the excess kurtosis.
var weibull = new Weibull( 4.0, 12.0 );
var kurtosis = weibull.kurtosis;
// returns ~-0.252
Weibull.prototype.mean
Returns the expected value.
var weibull = new Weibull( 4.0, 12.0 );
var mu = weibull.mean;
// returns ~10.877
Weibull.prototype.mode
Returns the mode.
var weibull = new Weibull( 4.0, 12.0 );
var mode = weibull.mode;
// returns ~11.167
Weibull.prototype.skewness
Returns the skewness.
var weibull = new Weibull( 4.0, 12.0 );
var skewness = weibull.skewness;
// returns ~-0.087
Weibull.prototype.stdev
Returns the standard deviation.
var weibull = new Weibull( 4.0, 12.0 );
var s = weibull.stdev;
// returns ~3.051
Weibull.prototype.variance
Returns the variance.
var weibull = new Weibull( 4.0, 12.0 );
var s2 = weibull.variance;
// returns ~9.311
Methods
Weibull.prototype.cdf( x )
Evaluates the cumulative distribution function (CDF).
var weibull = new Weibull( 2.0, 4.0 );
var y = weibull.cdf( 0.5 );
// returns ~0.016
Weibull.prototype.logcdf( x )
Evaluates the natural logarithm of the cumulative distribution function (logCDF).
var weibull = new Weibull( 2.0, 4.0 );
var y = weibull.logcdf( 0.8 );
// returns ~-3.239
Weibull.prototype.logpdf( x )
Evaluates the natural logarithm of the probability density function (PDF).
var weibull = new Weibull( 2.0, 4.0 );
var y = weibull.logpdf( 0.8 );
// returns ~-2.343
Weibull.prototype.mgf( t )
Evaluates the moment-generating function (MGF).
var weibull = new Weibull( 2.0, 4.0 );
var y = weibull.mgf( 0.5 );
// returns ~9.878
Weibull.prototype.pdf( x )
Evaluates the probability density function (PDF).
var weibull = new Weibull( 2.0, 4.0 );
var y = weibull.pdf( 0.8 );
// returns ~0.096
Weibull.prototype.quantile( p )
Evaluates the quantile function at probability p
.
var weibull = new Weibull( 2.0, 4.0 );
var y = weibull.quantile( 0.5 );
// returns ~3.33
y = weibull.quantile( 1.9 );
// returns NaN
Examples
var Weibull = require( '@stdlib/stats-base-dists-weibull-ctor' );
var weibull = new Weibull( 2.0, 4.0 );
var mu = weibull.mean;
// returns ~3.545
var mode = weibull.mode;
// returns ~2.828
var s2 = weibull.variance;
// returns ~3.434
var y = weibull.cdf( 0.8 );
// returns ~0.039
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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.