| /* |
| * 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.numbers.arrays; |
| |
| import org.junit.jupiter.api.Assertions; |
| import org.junit.jupiter.api.Test; |
| |
| /** |
| * Test cases for the {@link SafeNorm} class. |
| */ |
| public class SafeNormTest { |
| |
| @Test |
| public void testTiny() { |
| final double s = 1e-320; |
| final double[] v = new double[] {s, s}; |
| Assertions.assertEquals(Math.sqrt(2) * s, SafeNorm.value(v)); |
| } |
| |
| @Test |
| public void testBig() { |
| final double s = 1e300; |
| final double[] v = new double[] {s, s}; |
| Assertions.assertEquals(Math.sqrt(2) * s, SafeNorm.value(v)); |
| } |
| |
| @Test |
| public void testOne3D() { |
| final double s = 1; |
| final double[] v = new double[] {s, s, s}; |
| Assertions.assertEquals(Math.sqrt(3), SafeNorm.value(v)); |
| } |
| |
| @Test |
| public void testUnit3D() { |
| Assertions.assertEquals(1, SafeNorm.value(new double[] {1, 0, 0}), 0d); |
| Assertions.assertEquals(1, SafeNorm.value(new double[] {0, 1, 0}), 0d); |
| Assertions.assertEquals(1, SafeNorm.value(new double[] {0, 0, 1}), 0d); |
| } |
| |
| @Test |
| public void testSimple() { |
| final double[] v = new double[] {-0.9, 8.7, -6.5, -4.3, -2.1, 0, 1.2, 3.4, -5.6, 7.8, 9.0}; |
| final double expected = direct(v); |
| Assertions.assertEquals(expected, SafeNorm.value(v)); |
| } |
| |
| @Test |
| public void testZero() { |
| final double[] v = new double[] {0, 0, 0, 0, 0}; |
| Assertions.assertEquals(0d, SafeNorm.value(v)); |
| } |
| |
| @Test |
| public void testTinyAndSmallNormal() { |
| // Ensure the sum of the squared values for 'normal' values (1e-19*1e-19) |
| // is less than largest tiny value (1e-20) |
| final double[] v = new double[] {1e-20, 1e-19}; |
| Assertions.assertEquals(Math.sqrt(101) * 1e-20, SafeNorm.value(v)); |
| } |
| |
| /** |
| * Direct computation. |
| * |
| * @param v Array. |
| * @return the norm using direct summation. |
| */ |
| private double direct(double[] v) { |
| double n = 0; |
| for (int i = 0; i < v.length; i++) { |
| n += v[i] * v[i]; |
| } |
| return Math.sqrt(n); |
| } |
| } |