Chi distribution

The probability density function of :math:\chi-distribution is:

.. math::

f(x,\nu) = \frac{x^{\nu-1}e^{-x^2/2}}{2^{\nu/2-1}\Gamma(\nu/2)}

for :math:x\ge 0 and :math:k > 0 (degrees of freedom).

The cumulative distribution function is:

.. math::

F(x,\nu) = \frac{\gamma(\nu/2, x^2/2)}{\Gamma(\nu/2)}

The following plot shows the pdf.

.. image:: ../../../../tests/imgs/stats/continuous/chi/chipdf.png :align: center :width: 480