Standard Deviation

F distribution standard deviation.

The standard deviation for a F random variable is

for d1 > 0 and d2 > 4. Otherwise, the standard deviation is not defined.

Installation

npm install @stdlib/stats-base-dists-f-stdev

Usage

var stdev = require( '@stdlib/stats-base-dists-f-stdev' );

stdev( d1, d2 )

Returns the standard deviation of an F distribution with parameters d1 (numerator degrees of freedom) and d2 (denominator degrees of freedom).

var v = stdev( 4.0, 5.0 );
// returns ~3.118

v = stdev( 4.0, 12.0 );
// returns ~1.122

v = stdev( 8.0, 5.0 );
// returns ~2.764

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

var v = stdev( NaN, 5.0 );
// returns NaN

v = stdev( 3.0, NaN );
// returns NaN

If provided d1 <= 0, the function returns NaN.

var v = stdev( 0.0, 5.0 );
// returns NaN

v = stdev( -1.0, 5.0 );
// returns NaN

If provided d2 <= 4, the function returns NaN.

var v = stdev( 3.0, 4.0 );
// returns NaN

v = stdev( 3.0, -1.0 );
// returns NaN

Examples

var uniform = require( '@stdlib/random-array-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var EPS = require( '@stdlib/constants-float64-eps' );
var stdev = require( '@stdlib/stats-base-dists-f-stdev' );

var opts = {
    'dtype': 'float64'
};
var d1 = uniform( 10, EPS, 10.0, opts );
var d2 = uniform( 10, EPS, 20.0, opts );

logEachMap( 'd1: %0.4f, d2: %0.4f, SD(X;d1,d2): %0.4f', d1, d2, stdev );

C APIs

Usage

#include "stdlib/stats/base/dists/f/stdev.h"

stdlib_base_dists_f_stdev( d1, d2 )

Evaluates the standard deviation of an F distribution with parameters d1 (numerator degrees of freedom) and d2 (denominator degrees of freedom).

double out = stdlib_base_dists_f_stdev( 3.0, 5.0 );
// returns ~3.333

The function accepts the following arguments:

• d1: [in] double numerator degrees of freedom.
• d2: [in] double denominator degrees of freedom.

double stdlib_base_dists_f_stdev( const double d1, const double d2 );

Examples

#include "stdlib/stats/base/dists/f/stdev.h"
#include "stdlib/constants/float64/eps.h"
#include <stdlib.h>
#include <stdio.h>

static double random_uniform( const double min, const double max ) {
    double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
    return min + ( v*(max-min) );
}

int main( void ) {
    double d1;
    double d2;
    double y;
    int i;

    for ( i = 0; i < 25; i++ ) {
        d1 = random_uniform( STDLIB_CONSTANT_FLOAT64_EPS, 10.0 );
        d2 = random_uniform( STDLIB_CONSTANT_FLOAT64_EPS, 20.0 );
        y = stdlib_base_dists_f_stdev( d1, d2 );
        printf( "d1: %lf, d2: %lf, SD(X;d1,d2): %lf\n", d1, d2, 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 © 2016-2026. The Stdlib Authors.