@stdlib/stats-base-dists-poisson-quantile
v0.2.2
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Poisson distribution quantile function.
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Quantile Function
Poisson distribution quantile function.
The quantile function for a Poisson random variable returns for 0 <= p <= 1
the smallest nonnegative integer for which
where F
is the cumulative distribution function (CDF) of a Poisson distribution with mean parameter lambda > 0
.
Installation
npm install @stdlib/stats-base-dists-poisson-quantile
Usage
var quantile = require( '@stdlib/stats-base-dists-poisson-quantile' );
quantile( p, lambda )
Evaluates the quantile function for a Poisson distribution with mean parameter lambda
at a probability p
.
var y = quantile( 0.5, 2.0 );
// returns 2
y = quantile( 0.9, 4.0 );
// returns 7
y = quantile( 0.1, 200.0 );
// returns 182
If provided an input probability p
outside the interval [0,1]
, the function returns NaN
.
var y = quantile( 1.9, 0.5 );
// returns NaN
y = quantile( -0.1, 0.5 );
// returns NaN
If provided NaN
as any argument, the function returns NaN
.
var y = quantile( NaN, 1.0 );
// returns NaN
y = quantile( 0.0, NaN );
// returns NaN
If provided a negative lambda
, the function returns NaN
.
var y = quantile( 0.4, -1.0 );
// returns NaN
If provided lambda = 0
, the function evaluates the quantile function of a degenerate distribution centered at 0.0
.
var y = quantile( 0.1, 0.0 );
// returns 0.0
y = quantile( 0.9, 0.0 );
// returns 0.0
quantile.factory( lambda )
Returns a function for evaluating the quantile function of a Poisson distribution with mean parameter lambda
.
var myquantile = quantile.factory( 5.0 );
var y = myquantile( 0.4 );
// returns 4
y = myquantile( 0.8 );
// returns 7
y = myquantile( 1.0 );
// returns Infinity
Examples
var randu = require( '@stdlib/random-base-randu' );
var quantile = require( '@stdlib/stats-base-dists-poisson-quantile' );
var lambda;
var p;
var y;
var i;
for ( i = 0; i < 10; i++ ) {
p = randu();
lambda = randu() * 10.0;
y = quantile( p, lambda );
console.log( 'p: %d, λ: %d, Q(p;λ): %d', p.toFixed( 4 ), lambda.toFixed( 4 ), 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.