001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.math.ode;
019
020 import org.apache.commons.math.ode.events.EventHandler;
021 import org.apache.commons.math.ode.sampling.StepHandler;
022
023 /** This interface represents a first order integrator for
024 * differential equations.
025
026 * <p>The classes which are devoted to solve first order differential
027 * equations should implement this interface. The problems which can
028 * be handled should implement the {@link
029 * FirstOrderDifferentialEquations} interface.</p>
030 *
031 * @see FirstOrderDifferentialEquations
032 * @see StepHandler
033 * @see EventHandler
034 * @version $Revision: 674820 $ $Date: 2008-07-08 09:37:09 -0400 (Tue, 08 Jul 2008) $
035 * @since 1.2
036 */
037
038 public interface FirstOrderIntegrator extends ODEIntegrator {
039
040 /** Integrate the differential equations up to the given time.
041 * <p>This method solves an Initial Value Problem (IVP).</p>
042 * <p>Since this method stores some internal state variables made
043 * available in its public interface during integration ({@link
044 * #getCurrentSignedStepsize()}), it is <em>not</em> thread-safe.</p>
045 * @param equations differential equations to integrate
046 * @param t0 initial time
047 * @param y0 initial value of the state vector at t0
048 * @param t target time for the integration
049 * (can be set to a value smaller than <code>t0</code> for backward integration)
050 * @param y placeholder where to put the state vector at each successful
051 * step (and hence at the end of integration), can be the same object as y0
052 * @return stop time, will be the same as target time if integration reached its
053 * target, but may be different if some {@link EventHandler} stops it at some point.
054 * @throws IntegratorException if the integrator cannot perform integration
055 * @throws DerivativeException this exception is propagated to the caller if
056 * the underlying user function triggers one
057 */
058 public double integrate (FirstOrderDifferentialEquations equations,
059 double t0, double[] y0,
060 double t, double[] y)
061 throws DerivativeException, IntegratorException;
062
063 }