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Java example source code file (SigmoidTest.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

derivativestructure, eps, sigmoid, sigmoidtest, test, univariatefunction

The SigmoidTest.java Java example 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.math3.analysis.function;

import org.apache.commons.math3.analysis.UnivariateFunction;
import org.apache.commons.math3.analysis.differentiation.DerivativeStructure;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.DimensionMismatchException;

import org.junit.Assert;
import org.junit.Test;

/**
 * Test for class {@link Sigmoid}.
 */
public class SigmoidTest {
    private final double EPS = Math.ulp(1d);

    @Test
    public void testSomeValues() {
        final UnivariateFunction f = new Sigmoid();

        Assert.assertEquals(0.5, f.value(0), EPS);
        Assert.assertEquals(0, f.value(Double.NEGATIVE_INFINITY), EPS);
        Assert.assertEquals(1, f.value(Double.POSITIVE_INFINITY), EPS);
    }

    @Test
    public void testDerivative() {
        final Sigmoid f = new Sigmoid();
        final DerivativeStructure f0 = f.value(new DerivativeStructure(1, 1, 0, 0.0));

        Assert.assertEquals(0.25, f0.getPartialDerivative(1), 0);
    }

    @Test
    public void testDerivativesHighOrder() {
        DerivativeStructure s = new Sigmoid(1, 3).value(new DerivativeStructure(1, 5, 0, 1.2));
        Assert.assertEquals(2.5370495669980352859, s.getPartialDerivative(0), 5.0e-16);
        Assert.assertEquals(0.35578888129361140441, s.getPartialDerivative(1), 6.0e-17);
        Assert.assertEquals(-0.19107626464144938116,  s.getPartialDerivative(2), 6.0e-17);
        Assert.assertEquals(-0.02396830286286711696,  s.getPartialDerivative(3), 4.0e-17);
        Assert.assertEquals(0.21682059798981049049,   s.getPartialDerivative(4), 3.0e-17);
        Assert.assertEquals(-0.19186320234632658055,  s.getPartialDerivative(5), 2.0e-16);
    }

    @Test
    public void testDerivativeLargeArguments() {
        final Sigmoid f = new Sigmoid(1, 2);

        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, Double.NEGATIVE_INFINITY)).getPartialDerivative(1), 0);
        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, -Double.MAX_VALUE)).getPartialDerivative(1), 0);
        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, -1e50)).getPartialDerivative(1), 0);
        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, -1e3)).getPartialDerivative(1), 0);
        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, 1e3)).getPartialDerivative(1), 0);
        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, 1e50)).getPartialDerivative(1), 0);
        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, Double.MAX_VALUE)).getPartialDerivative(1), 0);
        Assert.assertEquals(0, f.value(new DerivativeStructure(1, 1, 0, Double.POSITIVE_INFINITY)).getPartialDerivative(1), 0);
    }

    @Test(expected=NullArgumentException.class)
    public void testParametricUsage1() {
        final Sigmoid.Parametric g = new Sigmoid.Parametric();
        g.value(0, null);
    }

    @Test(expected=DimensionMismatchException.class)
    public void testParametricUsage2() {
        final Sigmoid.Parametric g = new Sigmoid.Parametric();
        g.value(0, new double[] {0});
    }

    @Test(expected=NullArgumentException.class)
    public void testParametricUsage3() {
        final Sigmoid.Parametric g = new Sigmoid.Parametric();
        g.gradient(0, null);
    }

    @Test(expected=DimensionMismatchException.class)
    public void testParametricUsage4() {
        final Sigmoid.Parametric g = new Sigmoid.Parametric();
        g.gradient(0, new double[] {0});
    }

    @Test
    public void testParametricValue() {
        final double lo = 2;
        final double hi = 3;
        final Sigmoid f = new Sigmoid(lo, hi);

        final Sigmoid.Parametric g = new Sigmoid.Parametric();
        Assert.assertEquals(f.value(-1), g.value(-1, new double[] {lo, hi}), 0);
        Assert.assertEquals(f.value(0), g.value(0, new double[] {lo, hi}), 0);
        Assert.assertEquals(f.value(2), g.value(2, new double[] {lo, hi}), 0);
    }
}

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