Wald distribution

The probability density function for Wald distribution is:

.. math::

f(x) = \frac{1}{\sqrt{2\pi x^3}} \exp(- \frac{ (x-1)^2 }{ 2x })

for :math:x \ge 0.

The following plots show the pdf and cdf:

.. image:: ../../../../tests/imgs/stats/continuous/wald/waldpdf.png :align: center :width: 480

.. image:: ../../../../tests/imgs/stats/continuous/wald/waldcdf.png :align: center :width: 480