Constraint¶
- public class Constraint extends BasicEntity<ConstraintInstance>¶
This class represents an algebraic or logical constraint. In case the constraint is scalar, its values can be accessed via functions like
Constraint.body
andConstraint.dual
. All the AMPL suffixes for constraints (see http://www.ampl.com/NEW/suffbuiltin.html) are available through methods of this class with the same name (and methods ofConstraintInstance
for indexed constraints).Note that, since this class represents both algebraic and logical constraints, some suffixes might not be available for every entity.
An
UnsupportedOperationException
is thrown if one of such methods is called for a non-scalar constraint and if a method corresponding to a suffix which is not supported by the type of the constraint is called.The instances, represented by the class
ConstraintInstance
can be accessed via the methodConstraint.get
(see section Access to instances and values for further information on how to access instances).To gain access to all the values in an entity (for all instances and all suffixes for that entities), see
Entity.getValues
and theDataFrame
class.
Constructors¶
Constraint¶
Constraint¶
- Constraint(ConstraintBase impl)¶
Methods¶
astatus¶
body¶
- public double body()¶
Get the current value of the constraint’s body
defvar¶
- public int defvar()¶
Get the index in
_var
of “defined variable” substituted out by the constraint
dinit¶
- public double dinit()¶
Get the current initial guess for the constraint’s dual variable
dinit0¶
- public double dinit0()¶
Get the original initial guess for the constraint’s dual variable
drop¶
- public void drop()¶
Drop all instances in this constraint entity, corresponding to the AMPL code:
drop constraintname;
dual¶
- public double dual()¶
Get the current value of the constraint’s dual variable.
Note that dual values are often reset by the underlying AMPL interpreter by the presolve functionalities triggered by some methods. A possible workaround is to set the option
presolve
tofalse
(seeAMPL.setBoolOption
).
get¶
- public ConstraintInstance get()¶
Get the constraint instance (to be used only on scalar constraints)
- Throws
UnsupportedOperationException
– if the constraint is not scalar.
- Returns
The corresponding instance. @ throws IllegalStateException if the constraint has been deleted in the underlying AMPL interpreter
get¶
- public ConstraintInstance get(Object... key)¶
Get the constraint instance corresponding to the specified key. See Access to instances and values for further information on how the key can be specified.
- Parameters
key – The key to be found
- Throws
IllegalStateException
– if the entity has been deleted in the underlying AMPL interpreterIllegalArgumentException
– if trying to access an instance with the wrong number of keys (seeEntity.indexarity
)
- Returns
The constraint instance corresponding to the specified key. Returns
null
if the specified key is not present.
get¶
- public ConstraintInstance get(Tuple key)¶
Get the constraint instance corresponding to the specified key, expressed as a Tuple. See Access to instances and values for further information on how the key can be specified.
- Parameters
key – The indexing Tuple of the instance to be found
- Throws
IllegalStateException
– if the entity has been deleted in the underlying AMPL interpreterIllegalArgumentException
– if trying to access an instance with the wrong indexarity (seeEntity.indexarity
)
- Returns
The constraint instance corresponding to the specified key. Returns
null
if the specified key is not present.
impl¶
- ConstraintBase impl()¶
isLogical¶
- public boolean isLogical()¶
Check if the constraint is a logical constraint. The available suffixes differ between logical and non logical constraints. See http://www.ampl.com/NEW/suffbuiltin.html for a list of the available suffixes for algebraic constraints. The suffixes available for logical constraints are marked on the method description by “Valid only for logical constraints”.
- Returns
True if logical
iterator¶
- public Iterator<ConstraintInstance> iterator()¶
lb¶
- public double lb()¶
Get the current value of the constraint’s lower bound
lbs¶
- public double lbs()¶
Get the constraint lower bound sent to the solver (reflecting adjustment for fixed variables)
ldual¶
- public double ldual()¶
Get the current dual value associated with the lower bound
lslack¶
- public double lslack()¶
Get the slack at lower bound
body - lb
restore¶
- public void restore()¶
Restore all instances in this constraint entity, corresponding to the AMPL code:
restore constraintname;
setDual¶
- public void setDual(double dual)¶
Set the value of the dual variable associated to this constraint (valid only if the constraint is scalar). Equivalent to the AMPL statement:
let c := dual;
Note that dual values are often reset by the underlying AMPL interpreter by the presolve functionalities triggered by some methods. A possible workaround is to set the option
presolve
tofalse
(seeAMPL.setBoolOption
).- Parameters
dual – The value to be assigned to the dual variable
slack¶
- public double slack()¶
Constraint slack (the lesser of lslack and uslack)
sstatus¶
status¶
ub¶
- public double ub()¶
Get the current value of the constraint’s upper bound
ubs¶
- public double ubs()¶
Get the constraint upper bound sent to the solver (reflecting adjustment for fixed variables)
udual¶
- public double udual()¶
Get the current dual value associated with the upper bounds
uslack¶
- public double uslack()¶
Get the slack at upper bound
ub - body
val¶
- public double val()¶
Get the AMPL val suffix. Valid only for logical constraints.