Weibull minimum distribution

The probability density function for Weibull minimum distribution is:

.. math::

f(x, k) = k x^{k-1} \exp(-x^k)

for :math:x < 0, k > 0.

The following plots show the pdf and cdf:

.. image:: ../../../../tests/imgs/stats/continuous/weibull_min/weibull_minpdf.png :align: center :width: 480

.. image:: ../../../../tests/imgs/stats/continuous/weibull_min/weibull_mincdf.png :align: center :width: 480