Declaration: PerformFTest (Data1, Data2: TDoubleArray; OneSided: boolean; var Mean1, Mean2, Stdv1, Stdv2, FStatistic: double; var df1, df2: integer): double;
The function PerformFTest returns the probability associated with an F test (probability which indicates the likelihood that two samples have come from the same two underlying populations having the variance).

The parameters Data1 and Data2 contain the data. The parameter OneSided has to be TRUE for one-sided tests, or FALSE for two-sided tests. The function returns additional parameters obtained during the F test calculation:
Mean1, Mean2 means of the two samples
Stdv1, Stdv2 standard deviations of the two samples
FStatistic F statistic
df1, df2 degrees of freedom

Hint: Some background information on F tests can be found in the ebook "Fundamentals of Statistics"