    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
    021    /** This interface represents a first order integrator for
    022     * differential equations.
    023
    024     * <p>The classes which are devoted to solve first order differential
    025     * equations should implement this interface. The problems which can
    026     * be handled should implement the {@link
    027     * FirstOrderDifferentialEquations} interface.</p>
    028     *
    029     * @see FirstOrderDifferentialEquations
    030     * @see org.apache.commons.math.ode.sampling.StepHandler
    031     * @see org.apache.commons.math.ode.events.EventHandler
    032     * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 f??vr. 2011) $
    033     * @since 1.2
    034     */
    035
    036    public interface FirstOrderIntegrator extends ODEIntegrator {
    037
    038      /** Integrate the differential equations up to the given time.
    039       * <p>This method solves an Initial Value Problem (IVP).</p>
    040       * <p>Since this method stores some internal state variables made
    041       * available in its public interface during integration ({@link
    042       * #getCurrentSignedStepsize()}), it is <em>not</em> thread-safe.</p>
    043       * @param equations differential equations to integrate
    044       * @param t0 initial time
    045       * @param y0 initial value of the state vector at t0
    046       * @param t target time for the integration
    047       * (can be set to a value smaller than <code>t0</code> for backward integration)
    048       * @param y placeholder where to put the state vector at each successful
    049       *  step (and hence at the end of integration), can be the same object as y0
    050       * @return stop time, will be the same as target time if integration reached its
    051       * target, but may be different if some {@link
    052       * org.apache.commons.math.ode.events.EventHandler} stops it at some point.
    053       * @throws DerivativeException this exception is propagated to the caller if
    054       * the underlying user function triggers one
    055       * @throws IntegratorException if the integrator cannot perform integration
    056       */
    057      double integrate (FirstOrderDifferentialEquations equations,
    058                        double t0, double[] y0,
    059                        double t, double[] y) throws DerivativeException, IntegratorException;
    060
    061    }