Variance
The variance for a chi random variable is
where k >= 0 is the degrees of freedom.
Usage
var variance = require( '@stdlib/stats/base/dists/chi/variance' );
variance( k )
Returns the variance of a chi distribution with degrees of freedom k.
var v = variance( 9.0 );
// returns ~0.485
v = variance( 0.5 );
// returns ~0.272
If provided k < 0, the function returns NaN.
var v = variance( -1.0 );
// returns NaN
Examples
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var variance = require( '@stdlib/stats/base/dists/chi/variance' );
var k;
var v;
var i;
for ( i = 0; i < 10; i++ ) {
k = randu() * 20.0;
v = variance( k );
console.log( 'k: %d, Var(X,k): %d', k.toFixed( 4 ), v.toFixed( 4 ) );
}