de.termininistic.serein.examples.benchmarks.functions.unimodal.RosenbrockFunction.java Source code

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Here is the source code for de.termininistic.serein.examples.benchmarks.functions.unimodal.RosenbrockFunction.java

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/**
 * Copyright (C) 2015 Tobias Uhlig (tobias.uhlig@unibw.de)
 *
 * 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 de.termininistic.serein.examples.benchmarks.functions.unimodal;

import org.apache.commons.math3.linear.ArrayRealVector;
import org.apache.commons.math3.linear.RealVector;

import de.termininistic.serein.examples.benchmarks.functions.BenchmarkFunction;
import de.termininistic.serein.examples.benchmarks.functions.Domain;

public class RosenbrockFunction implements BenchmarkFunction {
    public final static Domain DEFAULT_DOMAIN = new Domain(-5, 10);
    private final Domain domain;

    public RosenbrockFunction() {
        this(DEFAULT_DOMAIN);
    }

    public RosenbrockFunction(Domain domain) {
        this.domain = domain;
    }

    @Override
    public Domain getDomain() {
        return domain;
    }

    @Override
    public RealVector getOptimum(int dimension) {
        return new ArrayRealVector(dimension, 1);
    }

    @Override
    public double map(RealVector v) {
        double fx = Double.MAX_VALUE;
        double[] x = v.toArray();
        int n = x.length;
        fx = 0.0;
        for (int i = 0; i < n - 1; i++) {
            double term1 = (x[i + 1] - x[i] * x[i]);
            fx += 100 * term1 * term1 + (x[i] - 1) * (x[i] - 1);
        }
        return fx;
    }

}