LinearConstraint.java
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* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.commons.math4.legacy.optim.linear;
import org.apache.commons.math4.legacy.linear.ArrayRealVector;
import org.apache.commons.math4.legacy.linear.RealVector;
/**
* A linear constraint for a linear optimization problem.
* <p>
* A linear constraint has one of the forms:
* <ul>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> = v</li>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> <= v</li>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> >= v</li>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> =
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> <=
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> >=
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* </ul>
* The c<sub>i</sub>, l<sub>i</sub> or r<sub>i</sub> are the coefficients of the constraints, the x<sub>i</sub>
* are the coordinates of the current point and v is the value of the constraint.
*
* @since 2.0
*/
public class LinearConstraint {
/** Coefficients of the constraint (left hand side). */
private final RealVector coefficients;
/** Relationship between left and right hand sides {@code (=, <=, >=)}. */
private final Relationship relationship;
/** Value of the constraint (right hand side). */
private final double value;
/**
* Build a constraint involving a single linear equation.
* <p>
* A linear constraint with a single linear equation has one of the forms:
* <ul>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> = v</li>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> <= v</li>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> >= v</li>
* </ul>
*
* @param coefficients The coefficients of the constraint (left hand side)
* @param relationship The type of (in)equality used in the constraint
* @param value The value of the constraint (right hand side)
*/
public LinearConstraint(final double[] coefficients,
final Relationship relationship,
final double value) {
this(new ArrayRealVector(coefficients), relationship, value);
}
/**
* Build a constraint involving a single linear equation.
* <p>
* A linear constraint with a single linear equation has one of the forms:
* <ul>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> = v</li>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> <= v</li>
* <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> >= v</li>
* </ul>
*
* @param coefficients The coefficients of the constraint (left hand side)
* @param relationship The type of (in)equality used in the constraint
* @param value The value of the constraint (right hand side)
*/
public LinearConstraint(final RealVector coefficients,
final Relationship relationship,
final double value) {
this.coefficients = coefficients;
this.relationship = relationship;
this.value = value;
}
/**
* Build a constraint involving two linear equations.
* <p>
* A linear constraint with two linear equation has one of the forms:
* <ul>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> =
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> <=
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> >=
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* </ul>
*
* @param lhsCoefficients The coefficients of the linear expression on the left hand side of the constraint
* @param lhsConstant The constant term of the linear expression on the left hand side of the constraint
* @param relationship The type of (in)equality used in the constraint
* @param rhsCoefficients The coefficients of the linear expression on the right hand side of the constraint
* @param rhsConstant The constant term of the linear expression on the right hand side of the constraint
*/
public LinearConstraint(final double[] lhsCoefficients, final double lhsConstant,
final Relationship relationship,
final double[] rhsCoefficients, final double rhsConstant) {
double[] sub = new double[lhsCoefficients.length];
for (int i = 0; i < sub.length; ++i) {
sub[i] = lhsCoefficients[i] - rhsCoefficients[i];
}
this.coefficients = new ArrayRealVector(sub, false);
this.relationship = relationship;
this.value = rhsConstant - lhsConstant;
}
/**
* Build a constraint involving two linear equations.
* <p>
* A linear constraint with two linear equation has one of the forms:
* <ul>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> =
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> <=
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> >=
* r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li>
* </ul>
*
* @param lhsCoefficients The coefficients of the linear expression on the left hand side of the constraint
* @param lhsConstant The constant term of the linear expression on the left hand side of the constraint
* @param relationship The type of (in)equality used in the constraint
* @param rhsCoefficients The coefficients of the linear expression on the right hand side of the constraint
* @param rhsConstant The constant term of the linear expression on the right hand side of the constraint
*/
public LinearConstraint(final RealVector lhsCoefficients, final double lhsConstant,
final Relationship relationship,
final RealVector rhsCoefficients, final double rhsConstant) {
this.coefficients = lhsCoefficients.subtract(rhsCoefficients);
this.relationship = relationship;
this.value = rhsConstant - lhsConstant;
}
/**
* Gets the coefficients of the constraint (left hand side).
*
* @return the coefficients of the constraint (left hand side).
*/
public RealVector getCoefficients() {
return coefficients;
}
/**
* Gets the relationship between left and right hand sides.
*
* @return the relationship between left and right hand sides.
*/
public Relationship getRelationship() {
return relationship;
}
/**
* Gets the value of the constraint (right hand side).
*
* @return the value of the constraint (right hand side).
*/
public double getValue() {
return value;
}
/** {@inheritDoc} */
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other instanceof LinearConstraint) {
LinearConstraint rhs = (LinearConstraint) other;
return relationship == rhs.relationship &&
value == rhs.value &&
coefficients.equals(rhs.coefficients);
}
return false;
}
/** {@inheritDoc} */
@Override
public int hashCode() {
return relationship.hashCode() ^
Double.valueOf(value).hashCode() ^
coefficients.hashCode();
}
}