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 differential equations set. 022 * 023 * <p>This interface should be implemented by all real first order 024 * differential equation problems before they can be handled by the 025 * integrators {@link FirstOrderIntegrator#integrate} method.</p> 026 * 027 * <p>A first order differential equations problem, as seen by an 028 * integrator is the time derivative <code>dY/dt</code> of a state 029 * vector <code>Y</code>, both being one dimensional arrays. From the 030 * integrator point of view, this derivative depends only on the 031 * current time <code>t</code> and on the state vector 032 * <code>Y</code>.</p> 033 * 034 * <p>For real problems, the derivative depends also on parameters 035 * that do not belong to the state vector (dynamical model constants 036 * for example). These constants are completely outside of the scope 037 * of this interface, the classes that implement it are allowed to 038 * handle them as they want.</p> 039 * 040 * @see FirstOrderIntegrator 041 * @see FirstOrderConverter 042 * @see SecondOrderDifferentialEquations 043 * 044 * @version $Revision: 811786 $ $Date: 2009-09-06 05:36:08 -0400 (Sun, 06 Sep 2009) $ 045 * @since 1.2 046 */ 047 048 public interface FirstOrderDifferentialEquations { 049 050 /** Get the dimension of the problem. 051 * @return dimension of the problem 052 */ 053 int getDimension(); 054 055 /** Get the current time derivative of the state vector. 056 * @param t current value of the independent <I>time</I> variable 057 * @param y array containing the current value of the state vector 058 * @param yDot placeholder array where to put the time derivative of the state vector 059 * @throws DerivativeException this exception is propagated to the caller if the 060 * underlying user function triggers one 061 */ 062 void computeDerivatives(double t, double[] y, double[] yDot) throws DerivativeException; 063 064 }