:orphan:

.. ****************************************************************************
.. CUI
..
.. The Advanced Framework for Simulation, Integration, and Modeling (AFSIM)
..
.. The use, dissemination or disclosure of data in this file is subject to
.. limitation or restriction. See accompanying README and LICENSE for details.
.. ****************************************************************************

WsfRandomVariable
-----------------

.. class:: WsfRandomVariable
   :constructible:
   :cloneable:

This class provides a limited distribution selection, using a generator separate from the simulation's random
number generator, for passage between script contexts where
there is a desire to maintain a repeatable but separate random number generation. The seed used
for this object is the same as specified globally in AFSIM.

Methods
=======

.. method:: void Set(string aDistribution, double aParameter1, double aParameter2, string aConstraint)

   This method provides the distribution, required parameters, and optional constraints for using
   the WsfRandomVariable_ object. This method **MUST** be called prior to its usage. It may be called
   multiple times to change the distribution and constraints associated with the script object.

   The passed string aDistribution represents the distribution to be used, with the following options:

      * "exponential" for an exponential distribution.
      * "log_normal" for a log normal distribution.
      * "normal" for a normal distribution.
      * "uniform" for a uniform distribution.
      * "constant" for a constant value. 
      
   Any other string value than those above defaults to a constant value (no distribution).

   The two parameter values are used based on the distribution type specified. If not required for the distribution,
   the parameter value is unused and any value may be provided.

      * For an exponential distribution, aParameter1 specifies the lambda (inverse of the mean).
      * For log normal and normal distributions, aParameter1 is the mean, aParameter2 is the standard deviation.
      * For uniform distributions, aParameter1 is the minimum value, aParameter2 is the maximum value.
      * For a constant, aParameter1 is the constant value.

   The passed string aConstraint specifies the optional constraints on the value of the random variable, s.t.

      * "positive" indicates draw results should be greater than zero.
      * "non_negative" indicates draw results should be greater than or equal to zero.
      * "no_constraint" indicates no constraints. 
      
   Any other string value than those above defaults to no constraints.

.. method:: double Draw()

   Draws a value from the distribution and parameters provided, and returns that value. In the case of
   constant usage, the constant value is provided.

.. method:: double LastDraw()

   Returns the last draw value generated. Does not call the random number generator
   and modify future values resulting from a draw.

.. method:: double GetFirstParameter()

   Returns the first parameter provided using the :method:`Set<WsfRandomVariable.Set>` method.

.. method:: double GetSecondParameter()

   Returns the second parameter provided using the :method:`Set<WsfRandomVariable.Set>` method. This value is only valid if used for the specified distribution.

.. method:: string GetDistribution()

   Returns the string name of the set distribution. If the :method:`Set<WsfRandomVariable.Set>` method has not been called, defaults to indicating a constant value.

.. method:: string GetConstraint()

   Returns any constraint applied using the :method:`Set<WsfRandomVariable.Set>` method. If the :method:`Set<WsfRandomVariable.Set>` method has not been called, defaults to indicating no constraint.