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+/*
+ * 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.math3.ode.nonstiff;
+
+
+/**
+ * This class implements the 3/8 fourth order Runge-Kutta
+ * integrator for Ordinary Differential Equations.
+ *
+ * <p>This method is an explicit Runge-Kutta method, its Butcher-array
+ * is the following one :
+ * <pre>
+ * 0 | 0 0 0 0
+ * 1/3 | 1/3 0 0 0
+ * 2/3 |-1/3 1 0 0
+ * 1 | 1 -1 1 0
+ * |--------------------
+ * | 1/8 3/8 3/8 1/8
+ * </pre>
+ * </p>
+ *
+ * @see EulerIntegrator
+ * @see ClassicalRungeKuttaIntegrator
+ * @see GillIntegrator
+ * @see MidpointIntegrator
+ * @see LutherIntegrator
+ * @since 1.2
+ */
+
+public class ThreeEighthesIntegrator extends RungeKuttaIntegrator {
+
+ /** Time steps Butcher array. */
+ private static final double[] STATIC_C = {
+ 1.0 / 3.0, 2.0 / 3.0, 1.0
+ };
+
+ /** Internal weights Butcher array. */
+ private static final double[][] STATIC_A = {
+ { 1.0 / 3.0 },
+ { -1.0 / 3.0, 1.0 },
+ { 1.0, -1.0, 1.0 }
+ };
+
+ /** Propagation weights Butcher array. */
+ private static final double[] STATIC_B = {
+ 1.0 / 8.0, 3.0 / 8.0, 3.0 / 8.0, 1.0 / 8.0
+ };
+
+ /** Simple constructor.
+ * Build a 3/8 integrator with the given step.
+ * @param step integration step
+ */
+ public ThreeEighthesIntegrator(final double step) {
+ super("3/8", STATIC_C, STATIC_A, STATIC_B, new ThreeEighthesStepInterpolator(), step);
+ }
+
+}