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Section: Random Number Generation
Generates random variables with an F-distribution. The general syntax for its use is
y = randf(n,m)
 where n and m are vectors of the number of degrees of freedom in the numerator and denominator of the chi-square random variables whose ratio defines the statistic. 
The statistic F_{n,m} is defined as the ratio of two chi-square random variables: 
![\[ F_{n,m} = \frac{\chi_n^2/n}{\chi_m^2/m} \]](form_142.png) 
The PDF is given by
![\[ f_{n,m} = \frac{m^{m/2}n^{n/2}x^{n/2-1}}{(m+nx)^{(n+m)/2}B(n/2,m/2)}, \]](form_143.png) 
 where B(a,b) is the beta function. 
Here we use randf to generate some F-distributed random variables, and then again using the randchi function:
--> randf(5*ones(1,9),7)
ans = 
 Columns 1 to 7
    0.5241    0.8414    0.4859    1.1266    0.4792    2.3743    2.9095 
 Columns 8 to 9
    0.5825    0.4244 
--> randchi(5*ones(1,9))./randchi(7*ones(1,9))
ans = 
 Columns 1 to 7
    0.3737    0.2363    1.5733    0.7003    1.1385    0.6337    0.4597 
 Columns 8 to 9
    0.2691    0.5190