FDIST

Calculates values for an F-distribution.

Syntax:

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:

$\frac{\Gamma (\frac{r_1+r_2}{2})(\frac{r_1}{r_2}{)}^{\frac{r_1}{2}}}{\Gamma (\frac{r_1}{2})\Gamma (\frac{r_2}{2})}\cdot {\int }_x^{\infty }\frac{t^{\frac{r_1}{2}-1}}{(1+\frac{r_1}{r_2}t{)}^{\frac{(r_1+r_2)}{2}}}dt$

Example:

FDIST(1, 4, 5)

returns approximately 0.485657.