# ComplexOrdinaryDifferentialEquation.java

/*
* Licensed to the Hipparchus project under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The Hipparchus project 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
*
* https://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.hipparchus.ode;
import org.hipparchus.complex.Complex;
/** This interface represents a first order differential equations set for {@link Complex complex state}.
*
* @see OrdinaryDifferentialEquation
* @see ComplexODEConverter
* @since 1.4
*
*/
public interface ComplexOrdinaryDifferentialEquation {
/** Get the dimension of the problem.
* @return dimension of the problem
*/
int getDimension();
/** Initialize equations at the start of an ODE integration.
* <p>
* This method is called once at the start of the integration. It
* may be used by the equations to initialize some internal data
* if needed.
* </p>
* <p>
* The default implementation does nothing.
* </p>
* @param t0 value of the independent <I>time</I> variable at integration start
* @param y0 array containing the value of the state vector at integration start
* @param finalTime target time for the integration
*/
default void init(double t0, Complex[] y0, double finalTime) {
// do nothing by default
}
/** Get the current time derivative of the state vector.
* @param t current value of the independent <I>time</I> variable
* @param y array containing the current value of the state vector
* @return time derivative of the state vector
*/
Complex[] computeDerivatives(double t, Complex[] y);
}