com.martinkampjensen.thesis.minimization.ObjectiveFunction.java Source code

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Here is the source code for com.martinkampjensen.thesis.minimization.ObjectiveFunction.java

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/**
 * Copyright 2010-2011 Martin Kamp Jensen
 * 
 * Licensed 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 com.martinkampjensen.thesis.minimization;

import org.apache.commons.math.analysis.MultivariateRealFunction;

import com.martinkampjensen.thesis.model.Model;

/**
 * An implementation of the {@link MultivariateRealFunction} interface of the
 * Apache Commons Math package.
 * <p>
 * This implementation enables the use of {@link Model}s for optimization.
 * 
 * @see <a href="http://commons.apache.org/math/">Apache Commons Math</a>
 */
public final class ObjectiveFunction implements MultivariateRealFunction {
    private final Model _model;

    /**
     * Constructs a new {@link MultivariateRealFunction} for use with the
     * optimization classes of the Apache Commons Math package.
     * 
     * @param model the model being optimized.
     * @throws NullPointerException if <code>model</code> is <code>null</code>.
     * @see <a href="http://commons.apache.org/math/">Apache Commons Math</a>
     */
    public ObjectiveFunction(Model model) {
        if (model == null) {
            throw new NullPointerException("model == null");
        }

        _model = model.copy();
    }

    /**
     * {@inheritDoc}
     * <p>
     * This implementation does not throw an {@link IllegalArgumentException} if
     * <code>point.length != model.size()</code> where <code>model</code> is
     * the {@link Model} used to construct this instance of
     * {@link ObjectiveFunction}. Instead, an ArrayIndexOutOfBoundsException is
     * thrown if <code>point.length &lt; model.size()</code>. This is to avoid
     * the overhead of checking <code>point.length</code> at each method
     * invocation.
     * 
     * @throws NullPointerException if <code>point == null</code>.
     * @throws ArrayIndexOutOfBoundsException if
     * <code>point.length &lt; model.size()</code> where <code>model</code> is
     * the {@link Model} used to construct this instance of
     * {@link ObjectiveFunction}.
     */
    @Override
    public double value(double[] point) {
        _model.setAngles(point);
        return _model.evaluate();
    }
}