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Java example source code file (StepInterpolator.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

externalizable, maxcountexceededexception, stepinterpolator

The StepInterpolator.java Java example 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.math3.ode.sampling;

import java.io.Externalizable;

import org.apache.commons.math3.exception.MaxCountExceededException;

/** This interface represents an interpolator over the last step
 * during an ODE integration.
 *
 * <p>The various ODE integrators provide objects implementing this
 * interface to the step handlers. These objects are often custom
 * objects tightly bound to the integrator internal algorithms. The
 * handlers can use these objects to retrieve the state vector at
 * intermediate times between the previous and the current grid points
 * (this feature is often called dense output).</p>
 * <p>One important thing to note is that the step handlers may be so
 * tightly bound to the integrators that they often share some internal
 * state arrays. This imply that one should <em>never use a direct
 * reference to a step interpolator outside of the step handler, either
 * for future use or for use in another thread. If such a need arise, the
 * step interpolator <em>must be copied using the dedicated
 * {@link #copy()} method.
 * </p>
 *
 * @see org.apache.commons.math3.ode.FirstOrderIntegrator
 * @see org.apache.commons.math3.ode.SecondOrderIntegrator
 * @see StepHandler
 * @since 1.2
 */

public interface StepInterpolator extends Externalizable {

  /**
   * Get the previous grid point time.
   * @return previous grid point time
   */
  double getPreviousTime();

  /**
   * Get the current grid point time.
   * @return current grid point time
   */
  double getCurrentTime();

  /**
   * Get the time of the interpolated point.
   * If {@link #setInterpolatedTime} has not been called, it returns
   * the current grid point time.
   * @return interpolation point time
   */
  double getInterpolatedTime();

  /**
   * Set the time of the interpolated point.
   * <p>Setting the time outside of the current step is now allowed, but
   * should be used with care since the accuracy of the interpolator will
   * probably be very poor far from this step. This allowance has been
   * added to simplify implementation of search algorithms near the
   * step endpoints.</p>
   * <p>Setting the time changes the instance internal state. This includes
   * the internal arrays returned in {@link #getInterpolatedState()},
   * {@link #getInterpolatedDerivatives()}, {@link
   * #getInterpolatedSecondaryState(int)} and {@link
   * #getInterpolatedSecondaryDerivatives(int)}. So if their content must be preserved
   * across several calls, user must copy them.</p>
   * @param time time of the interpolated point
   * @see #getInterpolatedState()
   * @see #getInterpolatedDerivatives()
   * @see #getInterpolatedSecondaryState(int)
   * @see #getInterpolatedSecondaryDerivatives(int)
   */
  void setInterpolatedTime(double time);

  /**
   * Get the state vector of the interpolated point.
   * <p>The returned vector is a reference to a reused array, so
   * it should not be modified and it should be copied if it needs
   * to be preserved across several calls to the associated
   * {@link #setInterpolatedTime(double)} method.</p>
   * @return state vector at time {@link #getInterpolatedTime}
   * @see #getInterpolatedDerivatives()
   * @see #getInterpolatedSecondaryState(int)
   * @see #getInterpolatedSecondaryDerivatives(int)
   * @see #setInterpolatedTime(double)
   * @exception MaxCountExceededException if the number of functions evaluations is exceeded
   */
  double[] getInterpolatedState() throws MaxCountExceededException;

  /**
   * Get the derivatives of the state vector of the interpolated point.
   * <p>The returned vector is a reference to a reused array, so
   * it should not be modified and it should be copied if it needs
   * to be preserved across several calls to the associated
   * {@link #setInterpolatedTime(double)} method.</p>
   * @return derivatives of the state vector at time {@link #getInterpolatedTime}
   * @see #getInterpolatedState()
   * @see #getInterpolatedSecondaryState(int)
   * @see #getInterpolatedSecondaryDerivatives(int)
   * @see #setInterpolatedTime(double)
   * @since 2.0
   * @exception MaxCountExceededException if the number of functions evaluations is exceeded
   */
  double[] getInterpolatedDerivatives() throws MaxCountExceededException;

  /** Get the interpolated secondary state corresponding to the secondary equations.
   * <p>The returned vector is a reference to a reused array, so
   * it should not be modified and it should be copied if it needs
   * to be preserved across several calls to the associated
   * {@link #setInterpolatedTime(double)} method.</p>
   * @param index index of the secondary set, as returned by {@link
   * org.apache.commons.math3.ode.ExpandableStatefulODE#addSecondaryEquations(
   * org.apache.commons.math3.ode.SecondaryEquations)
   * ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)}
   * @return interpolated secondary state at the current interpolation date
   * @see #getInterpolatedState()
   * @see #getInterpolatedDerivatives()
   * @see #getInterpolatedSecondaryDerivatives(int)
   * @see #setInterpolatedTime(double)
   * @since 3.0
   * @exception MaxCountExceededException if the number of functions evaluations is exceeded
   */
  double[] getInterpolatedSecondaryState(int index) throws MaxCountExceededException;

  /** Get the interpolated secondary derivatives corresponding to the secondary equations.
   * <p>The returned vector is a reference to a reused array, so
   * it should not be modified and it should be copied if it needs
   * to be preserved across several calls.</p>
   * @param index index of the secondary set, as returned by {@link
   * org.apache.commons.math3.ode.ExpandableStatefulODE#addSecondaryEquations(
   * org.apache.commons.math3.ode.SecondaryEquations)
   * ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)}
   * @return interpolated secondary derivatives at the current interpolation date
   * @see #getInterpolatedState()
   * @see #getInterpolatedDerivatives()
   * @see #getInterpolatedSecondaryState(int)
   * @see #setInterpolatedTime(double)
   * @since 3.0
   * @exception MaxCountExceededException if the number of functions evaluations is exceeded
   */
  double[] getInterpolatedSecondaryDerivatives(int index) throws MaxCountExceededException;

  /** Check if the natural integration direction is forward.
   * <p>This method provides the integration direction as specified by
   * the integrator itself, it avoid some nasty problems in
   * degenerated cases like null steps due to cancellation at step
   * initialization, step control or discrete events
   * triggering.</p>
   * @return true if the integration variable (time) increases during
   * integration
   */
  boolean isForward();

  /** Copy the instance.
   * <p>The copied instance is guaranteed to be independent from the
   * original one. Both can be used with different settings for
   * interpolated time without any side effect.</p>
   * @return a deep copy of the instance, which can be used independently.
   * @see #setInterpolatedTime(double)
   * @exception MaxCountExceededException if the number of functions evaluations is exceeded
   * during step finalization
   */
   StepInterpolator copy() throws MaxCountExceededException;

}

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