Commons Math example source code file (Expm1Function.java)

This example Commons Math source code file (Expm1Function.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Math tags/keywords

differentiableunivariaterealfunction, differentiableunivariaterealfunction, expm1function, expm1function, functionevaluationexception, functionevaluationexception, univariaterealfunction, univariaterealfunction

The Commons Math Expm1Function.java source code

/*
 * 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.math.analysis;

import org.apache.commons.math.FunctionEvaluationException;

/**
 * Auxillary class for testing purposes.
 *
 * @version $Revision: 786927 $ $Date: 2009-06-20 19:37:47 -0400 (Sat, 20 Jun 2009) $
 */
public class Expm1Function implements DifferentiableUnivariateRealFunction {

    public double value(double x) throws FunctionEvaluationException {
        // Math.expm1() is available in jdk 1.5 but not in jdk 1.4.2.
        return Math.exp(x) - 1.0;
    }

    public UnivariateRealFunction derivative() {
        return new UnivariateRealFunction() {
            public double value(double x) throws FunctionEvaluationException {
                return Math.exp(x);
            }
        };
    }
}