The F_PDF function computes the probability P that, in an F distribution with Dfn and Dfd degrees of freedom, a random variable X is less than or equal to a user-specified cutoff value V .
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.
Use the following command to compute the probability that a random variable X, from the F distribution with five degrees of freedom in the numerator and 24 degrees of freedom in the denominator, is less than or equal to 3.90. The result should be 0.990059.