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 /** This interface represents a first order integrator for
021 * differential equations.
022
023 * <p>The classes which are devoted to solve first order differential
024 * equations should implement this interface. The problems which can
025 * be handled should implement the {@link
026 * FirstOrderDifferentialEquations} interface.</p>
027 *
028 * @see FirstOrderDifferentialEquations
029 * @see org.apache.commons.math.ode.sampling.StepHandler
030 * @see org.apache.commons.math.ode.events.EventHandler
031 * @version $Revision: 811786 $ $Date: 2009-09-06 05:36:08 -0400 (Sun, 06 Sep 2009) $
032 * @since 1.2
033 */
034
035 public interface FirstOrderIntegrator extends ODEIntegrator {
036
037 /** Integrate the differential equations up to the given time.
038 * <p>This method solves an Initial Value Problem (IVP).</p>
039 * <p>Since this method stores some internal state variables made
040 * available in its public interface during integration ({@link
041 * #getCurrentSignedStepsize()}), it is <em>not</em> thread-safe.</p>
042 * @param equations differential equations to integrate
043 * @param t0 initial time
044 * @param y0 initial value of the state vector at t0
045 * @param t target time for the integration
046 * (can be set to a value smaller than <code>t0</code> for backward integration)
047 * @param y placeholder where to put the state vector at each successful
048 * step (and hence at the end of integration), can be the same object as y0
049 * @return stop time, will be the same as target time if integration reached its
050 * target, but may be different if some {@link
051 * org.apache.commons.math.ode.events.EventHandler} stops it at some point.
052 * @throws IntegratorException if the integrator cannot perform integration
053 * @throws DerivativeException this exception is propagated to the caller if
054 * the underlying user function triggers one
055 */
056 double integrate (FirstOrderDifferentialEquations equations,
057 double t0, double[] y0,
058 double t, double[] y) throws DerivativeException, IntegratorException;
059
060 }