.. java:import:: com.ampl Variable.Integrality

VariableInstance
================

.. java:package:: com.ampl
   :noindex:

.. java:type:: public class VariableInstance extends Instance<Variable>

   A decision variable instance. Each member of this class belongs to a single \ :java:ref:`Variable`\ . Note that accessors available here are replicated at \ :java:ref:`Variable`\  level for ease of use when dealing with scalar variables.

   All AMPL suffixes for an algebraic variable are available through methods with the same name in this class. See http://www.ampl.com/NEW/suffbuiltin.html for a list of the available suffixes.

   All the accessors in this class throw a :java:ref:`IllegalStateException` if the instance has been deleted in the underlying AMPL interpreter.

Methods
-------

.. java:method:: public String astatus()
   :outertype: VariableInstance

   Get the AMPL status (fixed, presolved, or substituted out)

.. java:method:: public int defeqn()
   :outertype: VariableInstance

   Get the index in \ ``_con``\  of "defining constraint" used to substitute variable out

.. java:method:: public double dual()
   :outertype: VariableInstance

   Get the dual value on defining constraint of variable substituted out

.. java:method:: public void fix()
   :outertype: VariableInstance

   Fix this variable instance to its current value

.. java:method:: public void fix(double value)
   :outertype: VariableInstance

   Fix this variable instance to the specified value

.. java:method:: public double init()
   :outertype: VariableInstance

   Get the current initial guess

.. java:method:: public double init0()
   :outertype: VariableInstance

   Get the original initial guess (set by \ ``:=``\  or \ ``default``\  or by a data statement)

.. java:method:: public double lb()
   :outertype: VariableInstance

   Returns the current lower bound

.. java:method:: public double lb0()
   :outertype: VariableInstance

   Returns the initial lower bounds, from the var declaration

.. java:method:: public double lb1()
   :outertype: VariableInstance

   Returns the weaker lower bound from AMPL's presolve phase

.. java:method:: public double lb2()
   :outertype: VariableInstance

   Returns the stronger lower bound from AMPL's presolve phase

.. java:method:: public double lrc()
   :outertype: VariableInstance

   Returns the reduced cost at lower bound

.. java:method:: public double lslack()
   :outertype: VariableInstance

   Return the slack at lower bound (\ ``val - lb``\ )

.. java:method:: @Override public String name()
   :outertype: VariableInstance

   Returns the variable name with possible subscripts as printed by the \ ``display``\  statement.

.. java:method:: public double rc()
   :outertype: VariableInstance

   Get the reduced cost (at the nearer bound)

.. java:method:: public void setValue(double value)
   :outertype: VariableInstance

   Set the current value of this variable instance (does not fix it), equivalent to the AMPL command \ ``let``\

   :param value: Value to be set

.. java:method:: public double slack()
   :outertype: VariableInstance

   Returns the bound slack which is the lesser of :java:ref:`lslack` and :java:ref:`uslack`.

.. java:method:: public String sstatus()
   :outertype: VariableInstance

   Solver status (basis status of variable)

.. java:method:: public String status()
   :outertype: VariableInstance

   AMPL status if not \ ``in``\ , otherwise solver status

.. java:method:: @Override public String toString()
   :outertype: VariableInstance

   Returns a string representation of this :java:ref:`VariableInstance` object. The format is as follows:

   .. parsed-literal::

      'var' name attrs ';'

   where ``name`` is the string returned by the :java:ref:`VariableInstance.name()` method and ``attrs`` represent attributes similar to those used in variable declarations.

   If the lower bound (``lb``) is equal to the upper bound (``ub``), the attributes contain ``'=' lb``.

   If the lower bound is not equal to the upper bound and ``Double.NEGATIVE_INFINITY`` , the attributes contain ``'>=' lb``.

   If the upper bound is not equal to the lower bound and ``Double.POSITIVE_INFINITY``, the attributes contain ``'<=' ub``.

   If the variable is integer, the attributes contain ``'integer'``.

   If the variable is binary, the attributes contain ``'binary'``.

.. java:method:: public double ub()
   :outertype: VariableInstance

   Returns the current upper bound.

.. java:method:: public double ub0()
   :outertype: VariableInstance

   Returns the initial upper bound, from the var declaration

.. java:method:: public double ub1()
   :outertype: VariableInstance

   Returns the weaker upper bound from AMPL's presolve phase

.. java:method:: public double ub2()
   :outertype: VariableInstance

   Returns the stronger upper bound from AMPL's presolve phase

.. java:method:: public void unfix()
   :outertype: VariableInstance

   Unfix this variable instance

.. java:method:: public double urc()
   :outertype: VariableInstance

   Returns the reduced cost at upper bound

.. java:method:: public double uslack()
   :outertype: VariableInstance

   Return the slack at upper bound (\ ``ub - val``\ )

.. java:method:: public double value()
   :outertype: VariableInstance

   Get the current value of this variable instance