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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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package org.apache.commons.math.ode;
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/** This interface represents a first order integrator for
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* differential equations.
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* <p>The classes which are devoted to solve first order differential
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* equations should implement this interface. The problems which can
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* be handled should implement the {@link
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* FirstOrderDifferentialEquations} interface.</p>
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* @see FirstOrderDifferentialEquations
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* @see SwitchingFunction
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* @version $Revision: 620312 $ $Date: 2008-02-10 12:28:59 -0700 (Sun, 10 Feb 2008) $
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public interface FirstOrderIntegrator {
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/** Get the name of the method.
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* @return name of the method
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public String getName();
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/** Set the step handler for this integrator.
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* The handler will be called by the integrator for each accepted
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* @param handler handler for the accepted steps
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public void setStepHandler (StepHandler handler);
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/** Get the step handler for this integrator.
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* @return the step handler for this integrator
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public StepHandler getStepHandler();
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/** Add a switching function to the integrator.
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* @param function switching function
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* @param maxCheckInterval maximal time interval between switching
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* function checks (this interval prevents missing sign changes in
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* case the integration steps becomes very large)
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* @param convergence convergence threshold in the event time search
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* @param maxIterationCount upper limit of the iteration count in
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* the event time search
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public void addSwitchingFunction(SwitchingFunction function,
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double maxCheckInterval,
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int maxIterationCount);
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/** Integrate the differential equations up to the given time.
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* <p>This method solves an Initial Value Problem (IVP).</p>
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* <p>Since this method stores some internal state variables made
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* available in its public interface during integration ({@link
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* #getCurrentSignedStepsize()}), it is <em>not</em> thread-safe.</p>
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* @param equations differential equations to integrate
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* @param t0 initial time
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* @param y0 initial value of the state vector at t0
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* @param t target time for the integration
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* (can be set to a value smaller than <code>t0</code> for backward integration)
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* @param y placeholder where to put the state vector at each successful
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* step (and hence at the end of integration), can be the same object as y0
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* @throws IntegratorException if the integrator cannot perform integration
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* @throws DerivativeException this exception is propagated to the caller if
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* the underlying user function triggers one
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public void integrate (FirstOrderDifferentialEquations equations,
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double t0, double[] y0,
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throws DerivativeException, IntegratorException;
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/** Get the current value of the step start time t<sub>i</sub>.
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* <p>This method can be called during integration (typically by
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* the object implementing the {@link FirstOrderDifferentialEquations
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* differential equations} problem) if the value of the current step that
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* is attempted is needed.</p>
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* <p>The result is undefined if the method is called outside of
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* calls to {@link #integrate}</p>
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* @return current value of the step start time t<sub>i</sub>
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public double getCurrentStepStart();
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/** Get the current signed value of the integration stepsize.
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* <p>This method can be called during integration (typically by
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* the object implementing the {@link FirstOrderDifferentialEquations
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* differential equations} problem) if the signed value of the current stepsize
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* that is tried is needed.</p>
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* <p>The result is undefined if the method is called outside of
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* calls to {@link #integrate}</p>
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* @return current signed value of the stepsize
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public double getCurrentSignedStepsize();