/*
* 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.util.FastMath;
import org.junit.Assert;
import org.junit.Test;
/**
* Test for all classes in org.apache.commons.math4.analysis.function that implement UnivariateFunction explicitly.
*/
public class UnivariateFunctionTest {
private final double EPS = Math.ulp(1d);
@Test
public void testAbs() {
Abs abs = new Abs();
Assert.assertEquals(5, abs.value(-5), EPS);
Assert.assertEquals(5, abs.value(5), EPS);
Assert.assertEquals(5.123, abs.value(-5.123), EPS);
Assert.assertEquals(5.123, abs.value(5.123), EPS);
Assert.assertEquals(0, abs.value(0), EPS);
}
@Test
public void testCeil() {
Ceil ceil = new Ceil();
Assert.assertEquals(-5, ceil.value(-5), EPS);
Assert.assertEquals(-4, ceil.value(-4.999), EPS);
Assert.assertEquals(0, ceil.value(0), EPS);
Assert.assertEquals(1, ceil.value(1), EPS);
Assert.assertEquals(2, ceil.value(1.000000001), EPS);
}
@Test
public void testFloor() {
Floor floor = new Floor();
Assert.assertEquals(-5, floor.value(-5), EPS);
Assert.assertEquals(-5, floor.value(-4.999), EPS);
Assert.assertEquals(0, floor.value(0), EPS);
Assert.assertEquals(1, floor.value(1), EPS);
Assert.assertEquals(1, floor.value(1.000000001), EPS);
}
@Test
public void testRint() {
//Rint function is round half even.
Rint rint = new Rint();
Assert.assertEquals(-5, rint.value(-5), EPS);
Assert.assertEquals(-4, rint.value(-4.5), EPS);
Assert.assertEquals(0, rint.value(0), EPS);
Assert.assertEquals(1, rint.value(1), EPS);
Assert.assertEquals(2, rint.value(1.5), EPS);
Assert.assertEquals(2, rint.value(2.5), EPS);
Assert.assertEquals(-1, rint.value(-0.99999999), EPS);
Assert.assertEquals(11, rint.value(10.99999999), EPS);
}
@Test
public void testSignum() {
Signum signum = new Signum();
Assert.assertEquals(-1, signum.value(-5), EPS);
Assert.assertEquals(-1, signum.value(-4.5), EPS);
Assert.assertEquals(0, signum.value(0), EPS);
Assert.assertEquals(-0, signum.value(-0), EPS);
Assert.assertEquals(1, signum.value(1), EPS);
Assert.assertEquals(1, signum.value(1.5), EPS);
Assert.assertEquals(1, signum.value(2.5), EPS);
Assert.assertEquals(-1, signum.value(-0.99999999), EPS);
Assert.assertEquals(1, signum.value(10.99999999), EPS);
}
@Test
public void testStepFunction() {
final double[] x = { -2, -0.5, 0, 1.9, 7.4, 21.3 };
final double[] y = { 4, -1, -5.5, 0.4, 5.8, 51.2 };
final UnivariateFunction f = new StepFunction(x, y);
Assert.assertEquals(4, f.value(Double.NEGATIVE_INFINITY), EPS);
Assert.assertEquals(4, f.value(-10), EPS);
Assert.assertEquals(-1, f.value(-0.4), EPS);
Assert.assertEquals(-5.5, f.value(0), EPS);
Assert.assertEquals(0.4, f.value(2), EPS);
Assert.assertEquals(5.8, f.value(10), EPS);
Assert.assertEquals(51.2, f.value(30), EPS);
Assert.assertEquals(51.2, f.value(Double.POSITIVE_INFINITY), EPS);
}
@Test
public void testUlp() {
Ulp ulp = new Ulp();
Assert.assertEquals(expectedUlp(1),ulp.value(1), EPS);
Assert.assertEquals(expectedUlp(1.123456789),ulp.value(1.123456789), EPS);
Assert.assertEquals(expectedUlp(-1),ulp.value(-1), EPS);
Assert.assertEquals(expectedUlp(-1.123456789),ulp.value(-1.123456789), EPS);
Assert.assertEquals(expectedUlp(0),ulp.value(0), EPS);
Assert.assertEquals(expectedUlp(500000000),ulp.value(500000000), EPS);
Assert.assertEquals(expectedUlp(-500000000),ulp.value(-500000000), EPS);
}
private double expectedUlp(double x) {
return FastMath.abs(x - Double.longBitsToDouble(Double.doubleToRawLongBits(x) ^ 1));
}
}