@stdlib/stats-base-dists-discrete-uniform-logcdf
v0.2.1
Published
Natural logarithm of the cumulative distribution function (CDF)for a discrete uniform distribution.
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Logarithm of Cumulative Distribution Function
Evaluate the natural logarithm of the cumulative distribution function for a discrete uniform distribution.
The cumulative distribution function for a discrete uniform random variable is
where a
is the minimum support and b
is the maximum support. The parameters must satisfy a <= b
.
Installation
npm install @stdlib/stats-base-dists-discrete-uniform-logcdf
Usage
var logcdf = require( '@stdlib/stats-base-dists-discrete-uniform-logcdf' );
logcdf( x, a, b )
Evaluates the natural logarithm of the cumulative distribution function (CDF) for a discrete uniform distribution with parameters a
(minimum support) and b
(maximum support).
var y = logcdf( 9.0, 0, 10 );
// returns ~-0.095
y = logcdf( 0.5, -2, 2 );
// returns ~-0.511
y = logcdf( -Infinity, 2, 4 );
// returns -Infinity
y = logcdf( Infinity, 2, 4 );
// returns 0.0
If a
or b
is not an integer value, the function returns NaN
.
var y = logcdf( 2.0, 1, 5.5 );
// returns NaN
If provided a > b
, the function returns NaN
.
var y = logcdf( 0.5, 3, 2);
// returns NaN
If provided NaN
for any parameter, the function returns NaN
.
var y = logcdf( NaN, 0, 1 );
// returns NaN
y = logcdf( 0.0, NaN, 1 );
// returns NaN
y = logcdf( 0.0, 0, NaN );
// returns NaN
logcdf.factory( a, b )
Returns a function for evaluating the natural logarithm of the cumulative distribution function of a discrete uniform distribution with parameters a
(minimum support) and b
(maximum support).
var myLogCDF = logcdf.factory( 0, 10 );
var y = myLogCDF( 0.5 );
// returns ~-2.398
y = myLogCDF( 8.0 );
// returns ~-0.201
Examples
var randint = require( '@stdlib/random-base-discrete-uniform' );
var randu = require( '@stdlib/random-base-randu' );
var logcdf = require( '@stdlib/stats-base-dists-discrete-uniform-logcdf' );
var randa = randint.factory( 0, 10 );
var randb = randint.factory();
var a;
var b;
var x;
var v;
var i;
for ( i = 0; i < 10; i++ ) {
x = randu() * 15.0;
a = randa();
b = randb( a, a+randa() );
v = logcdf( x, a, b );
console.log( 'x: %d, a: %d, b: %d, ln(F(x;a,b)): %d', x.toFixed( 4 ), a.toFixed( 4 ), b.toFixed( 4 ), v.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.