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Commons Math example source code file (TestProblem1.java)

This example Commons Math source code file (TestProblem1.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Math tags/keywords

override, override, testproblem1, testproblem1, testproblemabstract, testproblemabstract

The Commons Math TestProblem1.java source code

/*
 * 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.math.ode;

/**
 * This class is used in the junit tests for the ODE integrators.

 * <p>This specific problem is the following differential equation :
 * <pre>
 *    y' = -y
 * </pre>
 * the solution of this equation is a simple exponential function :
 * <pre>
 *   y (t) = y (t0) exp (t0-t)
 * </pre>
 * </p>

 */
public class TestProblem1
  extends TestProblemAbstract {

  /** Serializable version identifier. */
  private static final long serialVersionUID = 1977870815289373164L;

  /** theoretical state */
  private double[] y;

  /**
   * Simple constructor.
   */
  public TestProblem1() {
    super();
    double[] y0 = { 1.0, 0.1 };
    setInitialConditions(0.0, y0);
    setFinalConditions(4.0);
    double[] errorScale = { 1.0, 1.0 };
    setErrorScale(errorScale);
    y = new double[y0.length];
  }

  /**
   * Copy constructor.
   * @param problem problem to copy
   */
  public TestProblem1(TestProblem1 problem) {
    super(problem);
    y = problem.y.clone();
  }

  /** {@inheritDoc} */
  @Override
public TestProblem1 copy() {
    return new TestProblem1(this);
  }

  @Override
  public void doComputeDerivatives(double t, double[] y, double[] yDot) {

    // compute the derivatives
    for (int i = 0; i < n; ++i)
      yDot[i] = -y[i];

  }

  @Override
  public double[] computeTheoreticalState(double t) {
    double c = Math.exp (t0 - t);
    for (int i = 0; i < n; ++i) {
      y[i] = c * y0[i];
    }
    return y;
  }

}

Other Commons Math examples (source code examples)

Here is a short list of links related to this Commons Math TestProblem1.java source code file:

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