Blurb::
Aleatory uncertain discrete variable - negative binomial

Description::
The density function for the negative binomial distribution is given by:

.. math:: f(x) = \left(\begin{array}{c}{n+x-1}\\{x}\end{array}\right){p^n}{(1-p)^{x}},

where

- :math:`p`  is the probability of success per trial
- :math:`n`  is the number of successful trials
- :math:`x`  is the number of failures

Topics::
discrete_variables, aleatory_uncertain_variables

Examples::

Theory::
The negative binomial distribution is typically used to predict
the number of failures observed when repeating a test until a
total of :math:`n` successes have occurred, where each test has a
probability :math:`p` of success.

Faq::

See_Also::
