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    @stdlib/stats-base-dists-discrete-uniform-pmf
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    0.0.6 • Public • Published

    Probability Mass Function

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    Discrete uniform distribution probability mass function (PMF).

    The probability mass function (PMF) for a discrete uniform random variable is

    Probability mass function (PMF) for a discrete uniform distribution.

    where a is the minimum support and b is the maximum support of the distribution. The parameters must satisfy a <= b.

    Installation

    npm install @stdlib/stats-base-dists-discrete-uniform-pmf

    Usage

    var pmf = require( '@stdlib/stats-base-dists-discrete-uniform-pmf' );

    pmf( x, a, b )

    Evaluates the probability mass function (PMF) for a discrete uniform distribution with parameters a (minimum support) and b (maximum support).

    var y = pmf( 2.0, 0, 4 );
    // returns ~0.2
    
    y = pmf( 5.0, 0, 4 );
    // returns 0.0
    
    y = pmf( 3, -4, 4 );
    // returns ~0.111

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

    var y = pmf( NaN, -2, 2 );
    // returns NaN
    
    y = pmf( 1.0, NaN, 4 );
    // returns NaN
    
    y = pmf( 2.0, 0, NaN );
    // returns NaN

    If a or b is not an integer value, the function returns NaN.

    var y = pmf( 2.0, 1, 5.5 );
    // returns NaN

    If provided a > b, the function returns NaN.

    var y = pmf( 2.0, 3, 2 );
    // returns NaN

    pmf.factory( a, b )

    Returns a function for evaluating the PMF for a discrete uniform distribution with parameters a (minimum support) and b (maximum support).

    var myPDF = pmf.factory( 6, 7 );
    var y = myPDF( 7.0 );
    // returns 0.5
    
    y = myPDF( 5.0 );
    // returns 0.0

    Examples

    var randint = require( '@stdlib/random-base-discrete-uniform' );
    var pmf = require( '@stdlib/stats-base-dists-discrete-uniform-pmf' );
    
    var randa = randint.factory( 0, 10 );
    var randb = randint.factory();
    var a;
    var b;
    var x;
    var y;
    var i;
    
    for ( i = 0; i < 25; i++ ) {
        a = randa();
        x = randb( a, a+randa() );
        b = randb( a, a+randa() );
        y = pmf( x, a, b );
        console.log( 'x: %d, a: %d, b: %d, P(X=x;a,b): %d', x.toFixed( 4 ), a.toFixed( 4 ), b.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.

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    Copyright

    Copyright © 2016-2021. The Stdlib Authors.

    Install

    npm i @stdlib/stats-base-dists-discrete-uniform-pmf

    Homepage

    stdlib.io

    DownloadsWeekly Downloads

    35

    Version

    0.0.6

    License

    Apache-2.0

    Unpacked Size

    61.9 kB

    Total Files

    11

    Last publish

    Collaborators

    • stdlib-bot
    • kgryte
    • planeshifter
    • rreusser