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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.optim.nonlinear.scalar;
+
+import org.apache.commons.math3.analysis.MultivariateVectorFunction;
+import org.apache.commons.math3.optim.ConvergenceChecker;
+import org.apache.commons.math3.optim.OptimizationData;
+import org.apache.commons.math3.optim.PointValuePair;
+import org.apache.commons.math3.exception.TooManyEvaluationsException;
+
+/**
+ * Base class for implementing optimizers for multivariate scalar
+ * differentiable functions.
+ * It contains boiler-plate code for dealing with gradient evaluation.
+ *
+ * @since 3.1
+ */
+public abstract class GradientMultivariateOptimizer
+ extends MultivariateOptimizer {
+ /**
+ * Gradient of the objective function.
+ */
+ private MultivariateVectorFunction gradient;
+
+ /**
+ * @param checker Convergence checker.
+ */
+ protected GradientMultivariateOptimizer(ConvergenceChecker<PointValuePair> checker) {
+ super(checker);
+ }
+
+ /**
+ * Compute the gradient vector.
+ *
+ * @param params Point at which the gradient must be evaluated.
+ * @return the gradient at the specified point.
+ */
+ protected double[] computeObjectiveGradient(final double[] params) {
+ return gradient.value(params);
+ }
+
+ /**
+ * {@inheritDoc}
+ *
+ * @param optData Optimization data. In addition to those documented in
+ * {@link MultivariateOptimizer#parseOptimizationData(OptimizationData[])
+ * MultivariateOptimizer}, this method will register the following data:
+ * <ul>
+ * <li>{@link ObjectiveFunctionGradient}</li>
+ * </ul>
+ * @return {@inheritDoc}
+ * @throws TooManyEvaluationsException if the maximal number of
+ * evaluations (of the objective function) is exceeded.
+ */
+ @Override
+ public PointValuePair optimize(OptimizationData... optData)
+ throws TooManyEvaluationsException {
+ // Set up base class and perform computation.
+ return super.optimize(optData);
+ }
+
+ /**
+ * Scans the list of (required and optional) optimization data that
+ * characterize the problem.
+ *
+ * @param optData Optimization data.
+ * The following data will be looked for:
+ * <ul>
+ * <li>{@link ObjectiveFunctionGradient}</li>
+ * </ul>
+ */
+ @Override
+ protected void parseOptimizationData(OptimizationData... optData) {
+ // Allow base class to register its own data.
+ super.parseOptimizationData(optData);
+
+ // The existing values (as set by the previous call) are reused if
+ // not provided in the argument list.
+ for (OptimizationData data : optData) {
+ if (data instanceof ObjectiveFunctionGradient) {
+ gradient = ((ObjectiveFunctionGradient) data).getObjectiveFunctionGradient();
+ // If more data must be parsed, this statement _must_ be
+ // changed to "continue".
+ break;
+ }
+ }
+ }
+}