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Inverse gamma distribution mode.

The mode for an inverse gamma random variable is

Mode for an inverse gamma distribution.

where α > 0 is the shape parameter and β > 0 is the rate parameter.


npm install @stdlib/stats-base-dists-invgamma-mode


var mode = require( '@stdlib/stats-base-dists-invgamma-mode' );

mode( alpha, beta )

Returns the mode of an inverse gamma distribution with parameters alpha (shape parameter) and beta (rate parameter).

var v = mode( 1.0, 1.0 );
// returns 0.5

v = mode( 4.0, 12.0 );
// returns 2.4

v = mode( 8.0, 2.0 );
// returns ~0.222

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

var v = mode( NaN, 2.0 );
// returns NaN

v = mode( 2.0, NaN );
// returns NaN

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

var v = mode( 0.0, 1.0 );
// returns NaN

v = mode( -1.0, 1.0 );
// returns NaN

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

var v = mode( 1.0, 0.0 );
// returns NaN

v = mode( 1.0, -1.0 );
// returns NaN


var randu = require( '@stdlib/random-base-randu' );
var EPS = require( '@stdlib/constants-float64-eps' );
var mode = require( '@stdlib/stats-base-dists-invgamma-mode' );

var alpha;
var beta;
var v;
var i;

for ( i = 0; i < 10; i++ ) {
    alpha = ( randu()*10.0 ) + EPS;
    beta = ( randu()*10.0 ) + EPS;
    v = mode( alpha, beta );
    console.log( 'α: %d, β: %d, mode(X;α,β): %d', alpha.toFixed( 4 ), beta.toFixed( 4 ), v.toFixed( 4 ) );


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.






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npm i @stdlib/stats-base-dists-invgamma-mode



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