| /* |
| * 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.examples.jmh.arrays; |
| |
| import org.junit.jupiter.api.Assertions; |
| import org.junit.jupiter.api.Test; |
| |
| /** |
| * Tests for {@link DoublePrecision}. |
| */ |
| public class DoublePrecisionTest { |
| @Test |
| public void testSplitAssumptions() { |
| // The multiplier used to split the double value into high and low parts. |
| final double scale = (1 << 27) + 1; |
| // The upper limit above which a number may overflow during the split into a high part. |
| final double limit = 0x1.0p996; |
| Assertions.assertTrue(Double.isFinite(limit * scale)); |
| Assertions.assertTrue(Double.isFinite(-limit * scale)); |
| // Cannot make the limit the next power up |
| Assertions.assertEquals(Double.POSITIVE_INFINITY, limit * 2 * scale); |
| Assertions.assertEquals(Double.NEGATIVE_INFINITY, -limit * 2 * scale); |
| // Check the level for the safe upper limit of the exponent of the sum of the absolute |
| // components of the product |
| Assertions.assertTrue(Math.getExponent(2 * Math.sqrt(Double.MAX_VALUE)) - 2 > 508); |
| } |
| |
| @Test |
| public void testHighPart() { |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPart(Double.POSITIVE_INFINITY)); |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPart(Double.NEGATIVE_INFINITY)); |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPart(Double.NaN)); |
| // Any finite number should be split to a finite number |
| Assertions.assertTrue(Double.isFinite(DoublePrecision.highPart(Double.MAX_VALUE))); |
| Assertions.assertTrue(Double.isFinite(DoublePrecision.highPart(-Double.MAX_VALUE))); |
| } |
| |
| @Test |
| public void testHighPartUnscaled() { |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPartUnscaled(Double.POSITIVE_INFINITY)); |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPartUnscaled(Double.NEGATIVE_INFINITY)); |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPartUnscaled(Double.NaN)); |
| // Large finite numbers will overflow during the split |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPartUnscaled(Double.MAX_VALUE)); |
| Assertions.assertEquals(Double.NaN, DoublePrecision.highPartUnscaled(-Double.MAX_VALUE)); |
| } |
| |
| /** |
| * Test {@link DoublePrecision#productLow(double, double, double)} computes the same |
| * result as JDK 9 Math.fma(x, y, -x * y) for edge cases. |
| */ |
| @Test |
| public void testProductLow() { |
| assertProductLow(0.0, 1.0, Math.nextDown(Double.MIN_NORMAL)); |
| assertProductLow(0.0, -1.0, Math.nextDown(Double.MIN_NORMAL)); |
| assertProductLow(Double.NaN, 1.0, Double.POSITIVE_INFINITY); |
| assertProductLow(Double.NaN, 1.0, Double.NEGATIVE_INFINITY); |
| assertProductLow(Double.NaN, 1.0, Double.NaN); |
| assertProductLow(0.0, 1.0, Double.MAX_VALUE); |
| assertProductLow(Double.NaN, 2.0, Double.MAX_VALUE); |
| } |
| |
| private static void assertProductLow(double expected, double x, double y) { |
| Assertions.assertEquals(expected, DoublePrecision.productLow(x, y, x * y), 0.0); |
| } |
| |
| @Test |
| public void testIsNotNormal() { |
| for (double a : new double[] {Double.MAX_VALUE, 1.0, Double.MIN_NORMAL}) { |
| Assertions.assertFalse(DoublePrecision.isNotNormal(a)); |
| Assertions.assertFalse(DoublePrecision.isNotNormal(-a)); |
| } |
| for (double a : new double[] {Double.POSITIVE_INFINITY, 0.0, |
| Math.nextDown(Double.MIN_NORMAL), Double.NaN}) { |
| Assertions.assertTrue(DoublePrecision.isNotNormal(a)); |
| Assertions.assertTrue(DoublePrecision.isNotNormal(-a)); |
| } |
| } |
| } |