Crystalball distribution

The probability density function for crystalball distribution is:

.. math::

f(x,\beta,m)=\left\{\begin{matrix}
N\exp(-x^2/2) & \mbox{if } x > -\beta \\ 
NA(B-x)^{-m} & \mbox{if } x \le -\beta
\end{matrix}\right.

where :math:A=(m/|\beta|)^m \exp(-\beta^2/2), :math:B=m/|\beta|-|\beta| and :math:N is a normalization constant.

The following plot shows the pdf.

.. image:: ../../../../tests/imgs/stats/continuous/crystalball/crystalballpdf.png :align: center :width: 480