Cumulative Distribution Function

Logistic distribution cumulative distribution function.

The cumulative distribution function for a logistic random variable is

where mu is the location parameter and s > 0 is the scale parameter.

Installation

npm install @stdlib/stats-base-dists-logistic-cdf

Usage

var cdf = require( '@stdlib/stats-base-dists-logistic-cdf' );

cdf( x, mu, s )

Evaluates the cumulative distribution function (CDF) for a logistic distribution with parameters mu (location parameter) and s (scale parameter).

var y = cdf( 2.0, 0.0, 1.0 );
// returns ~0.881

y = cdf( 0.0, 0.0, 1.0 );
// returns 0.5

y = cdf( -1.0, 4.0, 2.0 );
// returns ~0.076

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

var y = cdf( NaN, 0.0, 1.0 );
// returns NaN

y = cdf( 0.0, NaN, 1.0 );
// returns NaN

y = cdf( 0.0, 0.0, NaN );
// returns NaN

If provided s < 0, the function returns NaN.

var y = cdf( 2.0, 0.0, -1.0 );
// returns NaN

If provided s = 0, the function evaluates the CDF of a degenerate distribution centered at mu.

var y = cdf( 2.0, 8.0, 0.0 );
// returns 0.0

y = cdf( 8.0, 8.0, 0.0 );
// returns 1.0

y = cdf( 10.0, 8.0, 0.0 );
// returns 1.0

cdf.factory( mu, s )

Returns a function for evaluating the cumulative distribution function of a logistic distribution with parameters mu (location parameter) and s (scale parameter).

var mycdf = cdf.factory( 10.0, 2.0 );

var y = mycdf( 10.0 );
// returns 0.5

y = mycdf( 8.0 );
// returns ~0.269

Examples

var randu = require( '@stdlib/random-base-randu' );
var cdf = require( '@stdlib/stats-base-dists-logistic-cdf' );

var mu;
var s;
var x;
var y;
var i;

for ( i = 0; i < 10; i++ ) {
    x = randu() * 10.0;
    mu = randu() * 10.0;
    s = randu() * 10.0;
    y = cdf( x, mu, s );
    console.log( 'x: %d, µ: %d, s: %d, F(x;µ,s): %d', x, mu, s, y );
}

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.