@stdlib/math-base-special-betaincinv
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    0.0.5 • Public • Published

    betaincinv

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    Inverse of the incomplete beta function.

    Installation

    npm install @stdlib/math-base-special-betaincinv

    Usage

    var betaincinv = require( '@stdlib/math-base-special-betaincinv' );

    betaincinv( p, a, b[, upper] )

    Inverts the regularized incomplete beta function. Contrary to the more commonly used definition, in this implementation the first parameter is the probability p and the second and third parameter are a and b. By default, the function inverts the lower regularized incomplete beta function. To invert the upper function instead, set the upper argument to true.

    var y = betaincinv( 0.2, 3.0, 3.0 );
    // returns ~0.327
    
    y = betaincinv( 0.4, 3.0, 3.0 );
    // returns ~0.446
    
    y = betaincinv( 0.4, 3.0, 3.0, true );
    // returns ~0.554
    
    y = betaincinv( 0.4, 1.0, 6.0 );
    // returns ~0.082
    
    y = betaincinv( 0.8, 1.0, 6.0 );
    // returns ~0.235

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

    var y = betaincinv( NaN, 1.0, 1.0 );
    // returns NaN
    
    y = betaincinv( 0.5, NaN, 1.0 );
    // returns NaN
    
    y = betaincinv( 0.5, 1.0, NaN );
    // returns NaN

    If provided a value outside [0,1] for p, the function returns NaN.

    var y = betaincinv( 1.2, 1.0, 1.0 );
    // returns NaN
    
    y = betaincinv( -0.5, 1.0, 1.0 );
    // returns NaN

    If provided a nonpositive a, the function returns NaN.

    var y = betaincinv( 0.5, -2.0, 2.0 );
    // returns NaN
    
    y = betaincinv( 0.5, 0.0, 2.0 );
    // returns NaN

    If provided a nonpositive b, the function returns NaN.

    var y = betaincinv( 0.5, 2.0, -2.0 );
    // returns NaN
    
    y = betaincinv( 0.5, 2.0, 0.0 );
    // returns NaN

    Examples

    var randu = require( '@stdlib/random-base-randu' );
    var betaincinv = require( '@stdlib/math-base-special-betaincinv' );
    
    var i;
    var p;
    var a;
    var b;
    
    for ( i = 0; i < 100; i++ ) {
        p = randu();
        a = randu() * 10.0;
        b = randu() * 10.0;
        console.log( 'p: %d, \t a: %d, \t b: %d, \t f(p,a,b): %d', p.toFixed( 4 ), a.toFixed( 4 ), b.toFixed( 4 ), betaincinv( p, a, b ) );
    }

    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/math-base-special-betaincinv

    Homepage

    stdlib.io

    DownloadsWeekly Downloads

    186

    Version

    0.0.5

    License

    Apache-2.0 AND BSL-1.0

    Unpacked Size

    40.6 kB

    Total Files

    9

    Last publish

    Collaborators

    • stdlib-bot
    • kgryte
    • planeshifter
    • rreusser