ncx2pdf (Statistics Toolbox)

Noncentral chi-square probability density function (pdf).

Syntax

Y = ncx2pdf(X,V,DELTA)

Description

Y = ncx2pdf(X,V,DELTA) returns the noncentral chi-square pdf with v degrees of freedom and positive noncentrality parameter, DELTA, at the values in X.

The size of Y is the common size of the input arguments. A scalar input functions as a constant matrix of the same size as the other inputs.

Some texts refer to this distribution as the generalized Rayleigh, Rayleigh-Rice, or Rice distribution.

Example

As the noncentrality parameter,

, increases, the distribution flattens as in the plot.

x = (0:0.1:10)';
p1 = ncx2pdf(x,4,2);
p = chi2pdf(x,4);
plot(x,p,'- -',x,p1,'-')

References

Johnson, N., and S. Kotz, Distributions in Statistics: Continuous Univariate Distributions-2, John Wiley and Sons, 1970. pp. 130-148.