1/*2* Licensed to the Apache Software Foundation (ASF) under one or more3* contributor license agreements. See the NOTICE file distributed with4* this work for additional information regarding copyright ownership.5* The ASF licenses this file to You under the Apache License, Version 2.06* (the "License"); you may not use this file except in compliance with7* the License. You may obtain a copy of the License at8*9* http://www.apache.org/licenses/LICENSE-2.010*11* Unless required by applicable law or agreed to in writing, software12* distributed under the License is distributed on an "AS IS" BASIS,13* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.14* See the License for the specific language governing permissions and15* limitations under the License.16*/17 18packageorg.apache.commons.math3.optimization.general; 19 20/**21* Available choices of update formulas for the β parameter22* in {@link NonLinearConjugateGradientOptimizer}.23* <p>24* The β parameter is used to compute the successive conjugate25* search directions. For non-linear conjugate gradients, there are26* two formulas to compute β:27* <ul>28* <li>Fletcher-Reeves formula</li>29* <li>Polak-Ribière formula</li>30* </ul>31* On the one hand, the Fletcher-Reeves formula is guaranteed to converge32* if the start point is close enough of the optimum whether the33* Polak-Ribière formula may not converge in rare cases. On the34* other hand, the Polak-Ribière formula is often faster when it35* does converge. Polak-Ribière is often used.36* <p>37* @see NonLinearConjugateGradientOptimizer38* @version $Id: ConjugateGradientFormula.java 1422230 2012-12-15 12:11:13Z erans $39* @deprecated As of 3.1 (to be removed in 4.0).40* @since 2.041*/42 @Deprecated 43publicenum ConjugateGradientFormula { 44 45/** Fletcher-Reeves formula. */46 FLETCHER_REEVES, 47 48/** Polak-Ribière formula. */49 POLAK_RIBIERE 50 51 }