/*
* 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.math4.analysis.function;
import org.apache.commons.math4.analysis.UnivariateFunction;
import org.apache.commons.math4.analysis.differentiation.DerivativeStructure;
import org.apache.commons.math4.analysis.function.Sigmoid;
import org.apache.commons.math4.exception.DimensionMismatchException;
import org.apache.commons.math4.exception.NullArgumentException;
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);
}
}