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 * (the "License"); you may not use this file except in compliance with
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 *
 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.commons.math3.ode.nonstiff;


This class implements the classical fourth order Runge-Kutta
integrator for Ordinary Differential Equations (it is the most
often used Runge-Kutta method).
This method is an explicit Runge-Kutta method, its Butcher-array
is the following one :
   0  |  0    0    0    0
  1/2 | 1/2   0    0    0
  1/2 |  0   1/2   0    0
   1  |  0    0    1    0
      |--------------------
      | 1/6  1/3  1/3  1/6


See Also:
EulerIntegrator
GillIntegrator
MidpointIntegrator
ThreeEighthesIntegrator
LutherIntegrator
Since:
1.2/**
 * This class implements the classical fourth order Runge-Kutta
 * integrator for Ordinary Differential Equations (it is the most
 * often used Runge-Kutta method).
 *
 * <p>This method is an explicit Runge-Kutta method, its Butcher-array
 * is the following one :
 * <pre>
 *    0  |  0    0    0    0
 *   1/2 | 1/2   0    0    0
 *   1/2 |  0   1/2   0    0
 *    1  |  0    0    1    0
 *       |--------------------
 *       | 1/6  1/3  1/3  1/6
 * </pre>
 * </p>
 *
 * @see EulerIntegrator
 * @see GillIntegrator
 * @see MidpointIntegrator
 * @see ThreeEighthesIntegrator
 * @see LutherIntegrator
 * @since 1.2
 */

public class ClassicalRungeKuttaIntegrator extends RungeKuttaIntegrator {

  
Time steps Butcher array. /** Time steps Butcher array. */
  private static final double[] STATIC_C = {
    1.0 / 2.0, 1.0 / 2.0, 1.0
  };

  
Internal weights Butcher array. /** Internal weights Butcher array. */
  private static final double[][] STATIC_A = {
    { 1.0 / 2.0 },
    { 0.0, 1.0 / 2.0 },
    { 0.0, 0.0, 1.0 }
  };

  
Propagation weights Butcher array. /** Propagation weights Butcher array. */
  private static final double[] STATIC_B = {
    1.0 / 6.0, 1.0 / 3.0, 1.0 / 3.0, 1.0 / 6.0
  };

  
Simple constructor.
Build a fourth-order Runge-Kutta integrator with the given
step.
Params:
step – integration step/** Simple constructor.
   * Build a fourth-order Runge-Kutta integrator with the given
   * step.
   * @param step integration step
   */
  public ClassicalRungeKuttaIntegrator(final double step) {
    super("classical Runge-Kutta", STATIC_C, STATIC_A, STATIC_B,
          new ClassicalRungeKuttaStepInterpolator(), step);
  }

}