Package org.ojalgo.optimisation
Class Presolvers
java.lang.Object
org.ojalgo.optimisation.Presolvers
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final ExpressionsBasedModel.Presolver
private static final NumberContext
static final ExpressionsBasedModel.Presolver
If the expression is linear and contributes to the objective function, then the contributions are transferred to the variables and the weight of the expression set to null.(package private) static final MathContext
static final ExpressionsBasedModel.Presolver
Calculates the min and max value of this expression based on the variables' individual bounds.private static final MathContext
static final ExpressionsBasedModel.VariableAnalyser
Verifies that the variable is actually referenced/used in some expression.(package private) static final MathContext
static final ExpressionsBasedModel.Presolver
Looks for constraint expressions with 0, 1 or 2 non-fixed variables. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic void
checkFeasibility
(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision, boolean relaxed) static boolean
checkSimilarity
(Collection<Expression> current, Expression potential) Checks if the potentialExpression
is similar to any in the current collection.(package private) static boolean
doCase0
(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) This constraint expression has 0 remaining free variable.(package private) static boolean
doCase1
(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) This constraint expression has 1 remaining free variable.(package private) static boolean
doCase2
(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) Checks if bounds on either of the variables (together with the expressions's bounds) implies tighter bounds on the other variable.(package private) static boolean
doCaseN
(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) Checks the sign of the limits and the sign of the expression parameters to deduce variables that in fact can only be zero.(package private) static BigDecimal
static boolean
reduce
(Collection<Expression> expressions)
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Field Details
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INTEGER
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LINEAR_OBJECTIVE
If the expression is linear and contributes to the objective function, then the contributions are transferred to the variables and the weight of the expression set to null. -
REDUNDANT_CONSTRAINT
Calculates the min and max value of this expression based on the variables' individual bounds. Then compares those with the expression's bounds. -
UNREFERENCED
Verifies that the variable is actually referenced/used in some expression. If not then that variable can either be fixed or marked as unbounded.2019-02-15: Turned this off. Very slow for large models 2019-02-22: Turned this on again, different implementation
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ZERO_ONE_TWO
Looks for constraint expressions with 0, 1 or 2 non-fixed variables. Transfers the constraints of the expressions to the variables and then (if possible) marks the expression as redundant. -
LEVEL
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SIMILARITY
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LOWER
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UPPER
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Constructor Details
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Presolvers
public Presolvers()
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Method Details
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checkFeasibility
public static void checkFeasibility(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision, boolean relaxed) -
checkSimilarity
Checks if the potentialExpression
is similar to any in the current collection.- Returns:
- true, if the potential
Expression
is found to be similar and marked as redundant by this method.
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reduce
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doCase0
static boolean doCase0(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) This constraint expression has 0 remaining free variable. It is entirely redundant. -
doCase1
static boolean doCase1(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) This constraint expression has 1 remaining free variable. The lower/upper limits can be transferred to that variable, and the expression marked as redundant. -
doCase2
static boolean doCase2(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) Checks if bounds on either of the variables (together with the expressions's bounds) implies tighter bounds on the other variable. -
doCaseN
static boolean doCaseN(Expression expression, Set<Structure1D.IntIndex> remaining, BigDecimal lower, BigDecimal upper, NumberContext precision) Checks the sign of the limits and the sign of the expression parameters to deduce variables that in fact can only be zero. -
findCommonLevel
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