## 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