Mean

Gumbel distribution expected value.

The mean for a Gumbel random variable with location μ and scale β is

double-struck upper E left-bracket upper X right-bracket equals mu plus beta gamma

where γ is the Euler–Mascheroni constant.

Usage

var mean = require( '@stdlib/math/base/dists/gumbel/mean' );

mean( mu, beta )

Returns the expected value for a Gumbel distribution with location parameter mu and scale parameter beta.

var y = mean( 2.0, 1.0 );
// returns ~1.577

y = mean( 0.0, 1.0 );
// returns ~1.577

y = mean( -1.0, 4.0 );
// returns ~2.964

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

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

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

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

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

y = mean( 0.0, -1.0 );
// returns NaN

Examples

var randu = require( '@stdlib/random/base/randu' );
var mean = require( '@stdlib/math/base/dists/gumbel/mean' );

var beta;
var mu;
var y;
var i;

for ( i = 0; i < 10; i++ ) {
    mu = ( randu()*10.0 ) - 5.0;
    beta = randu() * 20.0;
    y = mean( mu, beta );
    console.log( 'µ: %d, β: %d, h(X;µ,β): %d', mu.toFixed( 4 ), beta.toFixed( 4 ), y.toFixed( 4 ) );
}