@stdlib/stats-base-dists-frechet-stdev
v0.2.2
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Fréchet distribution standard deviation.
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Standard Deviation
Fréchet distribution standard deviation.
The standard deviation for a Fréchet random variable shape α > 0
, scale s > 0
, and location parameter m
is
where Γ
is the gamma function.
Installation
npm install @stdlib/stats-base-dists-frechet-stdev
Usage
var stdev = require( '@stdlib/stats-base-dists-frechet-stdev' );
stdev( alpha, s, m )
Returns the standard deviation for a Fréchet distribution with shape alpha > 0
, scale s > 0
, and location parameter m
.
var y = stdev( 3.0, 1.0, 1.0 );
// returns ~0.919
y = stdev( 3.0, 2.0, -3.0 );
// returns ~1.839
y = stdev( 5.0, 1.0, 2.0 );
// returns ~0.366
If 0 < alpha <= 2.0
, the function returns +Infinity
.
var y = stdev( 1.0, 1.0, 1.0 );
// returns Infinity
If provided NaN
as any argument, the function returns NaN
.
var y = stdev( NaN, 1.0, -2.0 );
// returns NaN
y = stdev( 1.0, NaN, -2.0 );
// returns NaN
y = stdev( 1.0, 1.0, NaN );
// returns NaN
If provided alpha <= 0
, the function returns NaN
.
var y = stdev( 0.0, 3.0, 2.0 );
// returns NaN
y = stdev( 0.0, -1.0, 2.0 );
// returns NaN
If provided s <= 0
, the function returns NaN
.
var y = stdev( 1.0, 0.0, 2.0 );
// returns NaN
y = stdev( 1.0, -1.0, 2.0 );
// returns NaN
Examples
var randu = require( '@stdlib/random-base-randu' );
var EPS = require( '@stdlib/constants-float64-eps' );
var stdev = require( '@stdlib/stats-base-dists-frechet-stdev' );
var alpha;
var m;
var s;
var y;
var i;
for ( i = 0; i < 10; i++ ) {
alpha = ( randu()*20.0 ) + EPS;
s = ( randu()*20.0 ) + EPS;
m = ( randu()*20.0 ) - 40.0;
y = stdev( alpha, s, m );
console.log( 'α: %d, s: %d, m: %d, SD(X;α,s,m): %d', alpha.toFixed( 4 ), s.toFixed( 4 ), m.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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.