| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.commons.math4.legacy.ode.sampling; |
| |
| import org.apache.commons.math4.legacy.core.RealFieldElement; |
| import org.apache.commons.math4.legacy.ode.FieldODEStateAndDerivative; |
| |
| /** This interface represents an interpolator over the last step |
| * during an ODE integration. |
| * |
| * <p>The various ODE integrators provide objects implementing this |
| * interface to the step handlers. These objects are often custom |
| * objects tightly bound to the integrator internal algorithms. The |
| * handlers can use these objects to retrieve the state vector at |
| * intermediate times between the previous and the current grid points |
| * (this feature is often called dense output).</p> |
| * |
| * @param <T> the type of the field elements |
| * @see org.apache.commons.math4.legacy.ode.FirstOrderFieldIntegrator |
| * @see FieldStepHandler |
| * @since 3.6 |
| */ |
| |
| public interface FieldStepInterpolator<T extends RealFieldElement<T>> { |
| |
| /** |
| * Get the state at previous grid point time. |
| * @return state at previous grid point time |
| */ |
| FieldODEStateAndDerivative<T> getPreviousState(); |
| |
| /** |
| * Get the state at current grid point time. |
| * @return state at current grid point time |
| */ |
| FieldODEStateAndDerivative<T> getCurrentState(); |
| |
| /** |
| * Get the state at interpolated time. |
| * <p>Setting the time outside of the current step is allowed, but |
| * should be used with care since the accuracy of the interpolator will |
| * probably be very poor far from this step. This allowance has been |
| * added to simplify implementation of search algorithms near the |
| * step endpoints.</p> |
| * @param time time of the interpolated point |
| * @return state at interpolated time |
| */ |
| FieldODEStateAndDerivative<T> getInterpolatedState(T time); |
| |
| /** Check if the natural integration direction is forward. |
| * <p>This method provides the integration direction as specified by |
| * the integrator itself, it avoid some nasty problems in |
| * degenerated cases like null steps due to cancellation at step |
| * initialization, step control or discrete events |
| * triggering.</p> |
| * @return true if the integration variable (time) increases during |
| * integration |
| */ |
| boolean isForward(); |
| |
| } |