.. 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.

Constructors
------------
VariableInstance
^^^^^^^^^^^^^^^^

.. java:constructor::  VariableInstance(Variable map, Object key)
   :outertype: VariableInstance

   Constructs a new variable with the lower bound, upper bound and value equal to the specified value. Initial guess is set to zero. Note that this method doesn't add the variable to the entity.

Methods
-------
astatus
^^^^^^^

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

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

copyFrom
^^^^^^^^

.. java:method::  void copyFrom(Instance<?> from)
   :outertype: VariableInstance

defeqn
^^^^^^

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

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

dual
^^^^

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

   Get the dual value on defining constraint of variable substituted out

fix
^^^

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

   Fix this variable instance to its current value

fix
^^^

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

   Fix this variable instance to the specified value

init
^^^^

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

   Get the current initial guess

init0
^^^^^

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

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

lb
^^

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

   Returns the current lower bound. See :ref:`secVariableSuffixesNotes`.

lb0
^^^

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

   Returns the initial lower bounds, from the var declaration

lb1
^^^

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

   Returns the weaker lower bound from AMPL's presolve phase

lb2
^^^

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

   Returns the stronger lower bound from AMPL's presolve phase

lrc
^^^

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

   Returns the reduced cost at lower bound

lslack
^^^^^^

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

   Return the slack at lower bound (\ ``val - lb``\ ). See :ref:`secVariableSuffixesNotes`.

name
^^^^

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

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

rc
^^

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

   Get the reduced cost (at the nearer bound)

setValue
^^^^^^^^

.. 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

slack
^^^^^

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

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

sstatus
^^^^^^^

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

   Solver status (basis status of variable)

status
^^^^^^

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

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

toString
^^^^^^^^

.. 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'``.

ub
^^

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

   Returns the current upper bound. See :ref:`secVariableSuffixesNotes`.

ub0
^^^

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

   Returns the initial upper bound, from the var declaration

ub1
^^^

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

   Returns the weaker upper bound from AMPL's presolve phase

ub2
^^^

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

   Returns the stronger upper bound from AMPL's presolve phase

unfix
^^^^^

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

   Unfix this variable instance

urc
^^^

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

   Returns the reduced cost at upper bound

uslack
^^^^^^

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

   Return the slack at upper bound (\ ``ub - val``\ ). See :ref:`secVariableSuffixesNotes`.

value
^^^^^

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

   Get the current value of this variable instance