##
F_PDF

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 ```
f_pdf.pro
```

in the ```
lib
```

subdirectory of the IDL distribution.

###
Calling Sequence

Result = F_PDF(*
V, Dfn, Dfd*
)

###
Arguments

####
V

An integer, single-, or double-precision floating-point scalar that specifies the cutoff value.

####
Dfn

A positive integer, single- or double-precision floating-point scalar that specifies the number of degrees of freedom of the F distribution numerator.

####
Dfd

A positive integer, single- or double-precision floating-point scalar that specifies the number of degrees of freedom of the F distribution denominator.

###
Example

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.

PRINT, F_PDF(3.90, 5, 24

IDL prints:

0.990059