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    @stdlib/stats-base-dists-poisson-ctor
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    0.0.6 • Public • Published

    Poisson

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    Poisson distribution constructor.

    Installation

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

    Usage

    var Poisson = require( '@stdlib/stats-base-dists-poisson-ctor' );

    Poisson( [lambda] )

    Returns an Poisson distribution object.

    var poisson = new Poisson();
    
    var lambda = poisson.mean;
    // returns 1.0

    By default, lambda = 1.0. To create a distribution having a different mean parameter lambda, provide a parameter value.

    var poisson = new Poisson( 4.0 );
    
    var lambda = poisson.mean;
    // returns 4.0

    poisson

    A Poisson distribution object has the following properties and methods...

    Writable Properties

    poisson.lambda

    Mean parameter of the distribution. lambda must be a positive number.

    var poisson = new Poisson( 2.0 );
    
    var lambda = poisson.lambda;
    // returns 2.0
    
    poisson.lambda = 3.0;
    
    lambda = poisson.lambda;
    // returns 3.0

    Computed Properties

    Poisson.prototype.entropy

    Returns the differential entropy.

    var poisson = new Poisson( 4.0 );
    
    var entropy = poisson.entropy;
    // returns ~2.087

    Poisson.prototype.kurtosis

    Returns the excess kurtosis.

    var poisson = new Poisson( 4.0 );
    
    var kurtosis = poisson.kurtosis;
    // returns 0.25

    Poisson.prototype.mean

    Returns the median.

    var poisson = new Poisson( 4.0 );
    
    var mu = poisson.mean;
    // returns 4.0

    Poisson.prototype.median

    Returns the median.

    var poisson = new Poisson( 4.0 );
    
    var median = poisson.median;
    // returns 4.0

    Poisson.prototype.mode

    Returns the mode.

    var poisson = new Poisson( 4.0 );
    
    var mode = poisson.mode;
    // returns 4.0

    Poisson.prototype.skewness

    Returns the skewness.

    var poisson = new Poisson( 4.0 );
    
    var skewness = poisson.skewness;
    // returns 0.5

    Poisson.prototype.stdev

    Returns the standard deviation.

    var poisson = new Poisson( 4.0 );
    
    var s = poisson.stdev;
    // returns 2.0

    Poisson.prototype.variance

    Returns the variance.

    var poisson = new Poisson( 4.0 );
    
    var s2 = poisson.variance;
    // returns 4.0

    Methods

    Poisson.prototype.cdf( x )

    Evaluates the cumulative distribution function (CDF).

    var poisson = new Poisson( 2.0 );
    
    var y = poisson.cdf( 0.5 );
    // returns ~0.135

    Poisson.prototype.logpmf( x )

    Evaluates the natural logarithm of the probability mass function (PMF).

    var poisson = new Poisson( 2.0 );
    
    var y = poisson.logpmf( 3.0 );
    // returns ~-1.712
    
    y = poisson.logpmf( 2.3 );
    // returns -Infinity

    Poisson.prototype.mgf( t )

    Evaluates the moment-generating function (MGF).

    var poisson = new Poisson( 2.0 );
    
    var y = poisson.mgf( 0.5 );
    // returns ~3.66

    Poisson.prototype.pmf( x )

    Evaluates the probability mass function (PMF).

    var poisson = new Poisson( 2.0 );
    
    var y = poisson.pmf( 3.0 );
    // returns ~0.18
    
    y = poisson.pmf( 2.3 );
    // returns 0.0

    Poisson.prototype.quantile( p )

    Evaluates the quantile function at probability p.

    var poisson = new Poisson( 2.0 );
    
    var y = poisson.quantile( 0.5 );
    // returns 2.0
    
    y = poisson.quantile( 1.9 );
    // returns NaN

    Examples

    var Poisson = require( '@stdlib/stats-base-dists-poisson-ctor' );
    
    var poisson = new Poisson( 2.0 );
    
    var mu = poisson.mean;
    // returns 2.0
    
    var mode = poisson.mode;
    // returns 2.0
    
    var s2 = poisson.variance;
    // returns 2.0
    
    var y = poisson.cdf( 0.8 );
    // returns ~0.135

    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.

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    License

    See LICENSE.

    Copyright

    Copyright © 2016-2021. The Stdlib Authors.

    Install

    npm i @stdlib/stats-base-dists-poisson-ctor

    Homepage

    stdlib.io

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    Version

    0.0.6

    License

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    52.4 kB

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    9

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    Collaborators

    • stdlib-bot
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    • planeshifter
    • rreusser