1 files changed, 150 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/optim/linear/LinearObjectiveFunction.java b/src/main/java/org/apache/commons/math3/optim/linear/LinearObjectiveFunction.java
new file mode 100644
index 0000000..6cff81f
--- /dev/null
+++ b/src/main/java/org/apache/commons/math3/optim/linear/LinearObjectiveFunction.java
@@ -0,0 +1,150 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * 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,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.math3.optim.linear;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import org.apache.commons.math3.analysis.MultivariateFunction;
+import org.apache.commons.math3.linear.MatrixUtils;
+import org.apache.commons.math3.linear.RealVector;
+import org.apache.commons.math3.linear.ArrayRealVector;
+import org.apache.commons.math3.optim.OptimizationData;
+
+/**
+ * An objective function for a linear optimization problem.
+ * <p>
+ * A linear objective function has one the form:
+ * <pre>
+ * c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> + d
+ * </pre>
+ * The c<sub>i</sub> and d are the coefficients of the equation,
+ * the x<sub>i</sub> are the coordinates of the current point.
+ * </p>
+ *
+ * @since 2.0
+ */
+public class LinearObjectiveFunction
+    implements MultivariateFunction,
+               OptimizationData,
+               Serializable {
+    /** Serializable version identifier. */
+    private static final long serialVersionUID = -4531815507568396090L;
+    /** Coefficients of the linear equation (c<sub>i</sub>). */
+    private final transient RealVector coefficients;
+    /** Constant term of the linear equation. */
+    private final double constantTerm;
+
+    /**
+     * @param coefficients Coefficients for the linear equation being optimized.
+     * @param constantTerm Constant term of the linear equation.
+     */
+    public LinearObjectiveFunction(double[] coefficients, double constantTerm) {
+        this(new ArrayRealVector(coefficients), constantTerm);
+    }
+
+    /**
+     * @param coefficients Coefficients for the linear equation being optimized.
+     * @param constantTerm Constant term of the linear equation.
+     */
+    public LinearObjectiveFunction(RealVector coefficients, double constantTerm) {
+        this.coefficients = coefficients;
+        this.constantTerm = constantTerm;
+    }
+
+    /**
+     * Gets the coefficients of the linear equation being optimized.
+     *
+     * @return coefficients of the linear equation being optimized.
+     */
+    public RealVector getCoefficients() {
+        return coefficients;
+    }
+
+    /**
+     * Gets the constant of the linear equation being optimized.
+     *
+     * @return constant of the linear equation being optimized.
+     */
+    public double getConstantTerm() {
+        return constantTerm;
+    }
+
+    /**
+     * Computes the value of the linear equation at the current point.
+     *
+     * @param point Point at which linear equation must be evaluated.
+     * @return the value of the linear equation at the current point.
+     */
+    public double value(final double[] point) {
+        return value(new ArrayRealVector(point, false));
+    }
+
+    /**
+     * Computes the value of the linear equation at the current point.
+     *
+     * @param point Point at which linear equation must be evaluated.
+     * @return the value of the linear equation at the current point.
+     */
+    public double value(final RealVector point) {
+        return coefficients.dotProduct(point) + constantTerm;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+        if (other instanceof LinearObjectiveFunction) {
+            LinearObjectiveFunction rhs = (LinearObjectiveFunction) other;
+          return (constantTerm == rhs.constantTerm) && coefficients.equals(rhs.coefficients);
+        }
+
+        return false;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public int hashCode() {
+        return Double.valueOf(constantTerm).hashCode() ^ coefficients.hashCode();
+    }
+
+    /**
+     * Serialize the instance.
+     * @param oos stream where object should be written
+     * @throws IOException if object cannot be written to stream
+     */
+    private void writeObject(ObjectOutputStream oos)
+        throws IOException {
+        oos.defaultWriteObject();
+        MatrixUtils.serializeRealVector(coefficients, oos);
+    }
+
+    /**
+     * Deserialize the instance.
+     * @param ois stream from which the object should be read
+     * @throws ClassNotFoundException if a class in the stream cannot be found
+     * @throws IOException if object cannot be read from the stream
+     */
+    private void readObject(ObjectInputStream ois)
+      throws ClassNotFoundException, IOException {
+        ois.defaultReadObject();
+        MatrixUtils.deserializeRealVector(this, "coefficients", ois);
+    }
+}