1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.math.ode; 19 20 import java.io.Externalizable; 21 22 /** This interface represents an interpolator over the last step 23 * during an ODE integration. 24 * 25 * <p>The various ODE integrators provide objects implementing this 26 * interface to the step handlers. These objects are often custom 27 * objects tightly bound to the integrator internal algorithms. The 28 * handlers can use these objects to retrieve the state vector at 29 * intermediate times between the previous and the current grid points 30 * (this feature is often called dense output).</p> 31 * 32 * @see FirstOrderIntegrator 33 * @see SecondOrderIntegrator 34 * @see StepHandler 35 * @version $Revision: 620312 $ $Date: 2008-02-10 12:28:59 -0700 (Sun, 10 Feb 2008) $ 36 * @since 1.2 37 */ 38 39 public interface StepInterpolator 40 extends Externalizable { 41 42 /** 43 * Get the previous grid point time. 44 * @return previous grid point time 45 */ 46 public double getPreviousTime(); 47 48 /** 49 * Get the current grid point time. 50 * @return current grid point time 51 */ 52 public double getCurrentTime(); 53 54 /** 55 * Get the time of the interpolated point. 56 * If {@link #setInterpolatedTime} has not been called, it returns 57 * the current grid point time. 58 * @return interpolation point time 59 */ 60 public double getInterpolatedTime(); 61 62 /** 63 * Set the time of the interpolated point. 64 * <p>Setting the time outside of the current step is now allowed, but 65 * should be used with care since the accuracy of the interpolator will 66 * probably be very poor far from this step. This allowance has been 67 * added to simplify implementation of search algorithms near the 68 * step endpoints.</p> 69 * <p>Setting the time changes the instance internal state. If a 70 * specific state must be preserved, a copy of the instance must be 71 * created using {@link #copy()}.</p> 72 * @param time time of the interpolated point 73 * @throws DerivativeException if this call induces an automatic 74 * step finalization that throws one 75 */ 76 public void setInterpolatedTime(double time) 77 throws DerivativeException; 78 79 /** 80 * Get the state vector of the interpolated point. 81 * @return state vector at time {@link #getInterpolatedTime} 82 */ 83 public double[] getInterpolatedState(); 84 85 /** Check if the natural integration direction is forward. 86 * <p>This method provides the integration direction as specified by 87 * the integrator itself, it avoid some nasty problems in 88 * degenerated cases like null steps due to cancellation at step 89 * initialization, step control or switching function 90 * triggering.</p> 91 * @return true if the integration variable (time) increases during 92 * integration 93 */ 94 public boolean isForward(); 95 96 /** Copy the instance. 97 * <p>The copied instance is guaranteed to be independent from the 98 * original one. Both can be used with different settings for 99 * interpolated time without any side effect.</p> 100 * @return a deep copy of the instance, which can be used independently. 101 * @throws DerivativeException if this call induces an automatic 102 * step finalization that throws one 103 * @see #setInterpolatedTime(double) 104 */ 105 public StepInterpolator copy() throws DerivativeException; 106 107 }