@stdlib/stats-base-dists-weibull-pdf
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Weibull distribution probability density function (PDF).
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Probability Density Function
Weibull distribution probability density function (PDF).
The probability density function (PDF) for a Weibull random variable is
where lambda > 0
and k > 0
are the respective scale and shape parameters of the distribution.
Installation
npm install @stdlib/stats-base-dists-weibull-pdf
Usage
var pdf = require( '@stdlib/stats-base-dists-weibull-pdf' );
pdf( x, k, lambda )
Evaluates the probability density function (PDF) for a Weibull distribution with shape parameter k
and scale parameter lambda
.
var y = pdf( 2.0, 1.0, 0.5 );
// returns ~0.037
y = pdf( -1.0, 4.0, 2.0 );
// returns 0.0
If provided NaN
as any argument, the function returns NaN
.
var y = pdf( NaN, 0.0, 1.0 );
// returns NaN
y = pdf( 0.0, NaN, 1.0 );
// returns NaN
y = pdf( 0.0, 0.0, NaN );
// returns NaN
If provided k <= 0
, the function returns NaN
.
var y = pdf( 2.0, 0.0, 1.0 );
// returns NaN
y = pdf( 2.0, -1.0, 1.0 );
// returns NaN
If provided lambda <= 0
, the function returns NaN
.
var y = pdf( 2.0, 1.0, 0.0 );
// returns NaN
y = pdf( 2.0, 1.0, -1.0 );
// returns NaN
pdf.factory( k, lambda )
Returns a function
for evaluating the PDF for a Weibull distribution with shape parameter k
and scale parameter lambda
.
var mypdf = pdf.factory( 2.0, 10.0 );
var y = mypdf( 12.0 );
// returns ~0.057
y = mypdf( 5.0 );
// returns ~0.078
Examples
var randu = require( '@stdlib/random-base-randu' );
var pdf = require( '@stdlib/stats-base-dists-weibull-pdf' );
var lambda;
var k;
var x;
var y;
var i;
for ( i = 0; i < 10; i++ ) {
x = randu() * 10.0;
lambda = randu() * 10.0;
k = randu() * 10.0;
y = pdf( x, lambda, k );
console.log( 'x: %d, k: %d, λ: %d, f(x;k,λ): %d', x.toFixed( 4 ), k.toFixed( 4 ), lambda.toFixed( 4 ), y.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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.