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Noncentral F cumulative distribution function (cdf).
Syntax
P = ncfcdf(X,NU1,NU2,DELTA)
Description
P = ncfcdf(X,NU1,NU2,DELTA) returns the noncentral F cdf with numerator degrees of freedom (df), NU1, denominator df, NU2, and positive noncentrality parameter, DELTA, at the values in X.
The size of P is the common size of the input arguments. A scalar input functions as a constant matrix of the same size as the other inputs.
The noncentral F cdf is:
where I(x|a,b) is the incomplete beta function with parameters a and b.
Example
Compare the noncentral F cdf with
= 10 to the F cdf with the same number of numerator and denominator degrees of freedom (5 and 20 respectively).
x = (0.01:0.1:10.01)'; p1 = ncfcdf(x,5,20,10); p = fcdf(x,5,20); plot(x,p,'- -',x,p1,'-')
References