Mean

Half-normal distribution expected value.

The expected value for a half-normal random variable with scale parameter σ > 0 is

Installation

npm install @stdlib/stats-base-dists-halfnormal-mean

Usage

var mean = require( '@stdlib/stats-base-dists-halfnormal-mean' );

mean( sigma )

Returns the expected value for a half-normal distribution with scale parameter sigma.

var y = mean( 1.0 );
// returns ~0.798

y = mean( 4.0 );
// returns ~3.192

y = mean( 0.5 );
// returns ~0.399

If provided NaN, the function returns NaN.

var y = mean( NaN );
// returns NaN

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

var y = mean( 0.0 );
// returns NaN

y = mean( -1.0 );
// returns NaN

Examples

var uniform = require( '@stdlib/random-array-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var mean = require( '@stdlib/stats-base-dists-halfnormal-mean' );

var opts = {
    'dtype': 'float64'
};
var sigma = uniform( 10, 0.1, 20.0, opts );

logEachMap( 'σ: %lf, E(X;σ): %lf', sigma, mean );

C APIs

Usage

#include "stdlib/stats/base/dists/halfnormal/mean.h"

stdlib_base_dists_halfnormal_mean( sigma )

Returns the expected value for a half-normal distribution with scale parameter sigma.

• sigma: [in] double scale parameter.

double stdlib_base_dists_halfnormal_mean( const double sigma );

Examples

#include "stdlib/stats/base/dists/halfnormal/mean.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 sigma;
    double y;
    int i;

    for ( i = 0; i < 10; i++ ) {
        sigma = random_uniform( 0.1, 20.0 );
        y = stdlib_base_dists_halfnormal_mean( sigma );
        printf( "σ: %lf, E(X;σ): %lf\n", sigma, 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.