Calculates values for an F-distribution.
FDIST(x, r1, r2)
r1 and r2, which are positive integers, are the degrees of freedom parameters for the F-distribution.
x must be greater than or equal to 0.
FDIST returns the area of the right tail of the probability density function for the F-distribution, calculating:
FDIST(1, 4, 5)
returns approximately 0.485657.