PF

pf

The F (or Fisher-Snedecor) cumulative distribution function

         F = pf(x,df1,df2)
	Input	x	real
		df1,df2 degrees of freedom
		(x,df1,df2 can be scalar or matrix with common size)

	Output	F	for each element of x, F=Prob((X/df1)/(Y/df2) < x)
			where X and Y are independent Chisquare random 
			variables with one degree of freedom