Variance
Chi-squared distribution variance.
The variance for a chi-squared random variable is
where k >= 0
is the degrees of freedom.
Usage
var variance = require( '@stdlib/stats/base/dists/chisquare/variance' );
variance( k )
Returns the variance of a chi-squared distribution with degrees of freedom k
.
var v = variance( 9.0 );
// returns 18.0
v = variance( 0.5 );
// returns 1.0
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/chisquare/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 ) );
}