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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.optimization.general;
/**
* Available choices of update formulas for the β parameter
* in {@link NonLinearConjugateGradientOptimizer}.
*
* The β parameter is used to compute the successive conjugate
* search directions. For non-linear conjugate gradients, there are
* two formulas to compute β:
*
* - Fletcher-Reeves formula
* - Polak-Ribière formula
*
* On the one hand, the Fletcher-Reeves formula is guaranteed to converge
* if the start point is close enough of the optimum whether the
* Polak-Ribière formula may not converge in rare cases. On the
* other hand, the Polak-Ribière formula is often faster when it
* does converge. Polak-Ribière is often used.
*
* @see NonLinearConjugateGradientOptimizer
* @deprecated As of 3.1 (to be removed in 4.0).
* @since 2.0
*/
@Deprecated
public enum ConjugateGradientFormula {
/** Fletcher-Reeves formula. */
FLETCHER_REEVES,
/** Polak-Ribière formula. */
POLAK_RIBIERE
}