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Mean

Log-logistic distribution mean.

The mean for a log-logistic random variable with scale α > 0 and shape β > 1 is

$$\mathbb{E}[X] = \frac{\alpha \pi/\beta}{\sin(\pi/\beta)}$$

Usage

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

mean( alpha, beta )

Returns the mean for a log-logistic distribution with scale parameter alpha and shape parameter beta.

var y = mean( 1.0, 2.0 );
// returns ~1.571

y = mean( 4.0, 3.0 );
// returns ~4.837

y = mean( 2.0, 5.0 );
// returns ~2.138

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

var y = mean( NaN, 2.0 );
// returns NaN

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

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

var y = mean( 0.0, 2.0 );
// returns NaN

y = mean( -1.0, 2.0 );
// returns NaN

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

var y = mean( 2.0, 0.0 );
// returns NaN

y = mean( 2.0, -1.0 );
// returns NaN

If provided beta <= 1, the function returns NaN.

var y = mean( 2.0, 1.0 );
// returns NaN

y = mean( 2.0, 0.5 );
// 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/log-logistic/mean' );

var opts = {
    'dtype': 'float64'
};
var alpha = uniform( 10, 0.1, 10.0, opts );
var beta = uniform( 10, 1.1, 10.0, opts );

logEachMap( 'alpha: %0.4f, beta: %0.4f, Mean(X;alpha,beta): %0.4f', alpha, beta, mean );

C APIs

Usage

#include "stdlib/stats/base/dists/log-logistic/mean.h"

stdlib_base_dists_log_logistic_mean( alpha, beta )

Returns the mean for a log-logistic distribution with scale alpha and shape beta.

double out = stdlib_base_dists_log_logistic_mean( 1.0, 2.0 );
// returns ~1.571

The function accepts the following arguments:

  • alpha: [in] double scale parameter.
  • beta: [in] double shape parameter.
double stdlib_base_dists_log_logistic_mean( const double alpha, const double beta );

Examples

#include "stdlib/stats/base/dists/log-logistic/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 alpha;
    double beta;
    double v;
    int i;

    for ( i = 0; i < 25; i++ ) {
        alpha = random_uniform( 0.1, 10.0 );
        beta = random_uniform( 1.1, 10.0 );
        v = stdlib_base_dists_log_logistic_mean( alpha, beta );
        printf( "alpha: %lf, beta: %lf, Mean(X;alpha,beta): %lf\n", alpha, beta, v );
    }
}