commons/src/main/java/org/apache/hama/commons/math/Tanh.java

/**
 * 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.hama.commons.math;

/**
 * Tanh function.
 * 
 */
public class Tanh extends DoubleFunction {

  @Override
  public double apply(double value) {
    return Math.tanh(value);
  }

  @Override
  public double applyDerivative(double value) {
    return 1 - value * value;
  }
  
}