266 lines
9.6 KiB
C#
266 lines
9.6 KiB
C#
#region Apache License 2.0
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/*
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Nuclex .NET Framework
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Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#endregion // Apache License 2.0
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#if UNITTEST
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using System;
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using System.Collections.Generic;
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using NUnit.Framework;
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namespace Nuclex.Support {
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/// <summary>Unit Test for the FloatHelper class</summary>
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[TestFixture]
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internal class FloatHelperTest {
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/// <summary>Tests the floating point value comparison helper</summary>
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[Test]
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public void UlpDistancesOnFloatsCompareAsEqual() {
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(0.00000001f, 0.0000000100000008f, 1),
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"Minimal difference between very small floating point numbers is considered equal"
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);
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Assert.IsFalse(
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FloatHelper.AreAlmostEqual(0.00000001f, 0.0000000100000017f, 1),
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"Larger difference between very small floating point numbers is not considered equal"
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);
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(1000000.00f, 1000000.06f, 1),
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"Minimal difference between very large floating point numbers is considered equal"
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);
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Assert.IsFalse(
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FloatHelper.AreAlmostEqual(1000000.00f, 1000000.13f, 1),
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"Larger difference between very large floating point numbers is not considered equal"
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);
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}
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/// <summary>Tests the double precision floating point value comparison helper</summary>
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[Test]
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public void UlpDistancesOnDoublesCompareAsEqual() {
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(0.00000001, 0.000000010000000000000002, 1),
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"Minimal difference between very small double precision floating point " +
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"numbers is considered equal"
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);
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Assert.IsFalse(
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FloatHelper.AreAlmostEqual(0.00000001, 0.000000010000000000000004, 1),
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"Larger difference between very small double precision floating point " +
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"numbers is not considered equal"
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);
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(1000000.00, 1000000.0000000001, 1),
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"Minimal difference between very large double precision floating point " +
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"numbers is considered equal"
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);
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Assert.IsFalse(
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FloatHelper.AreAlmostEqual(1000000.00, 1000000.0000000002, 1),
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"Larger difference between very large double precision floating point " +
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"numbers is not considered equal"
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);
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}
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/// <summary>Tests the integer reinterpretation functions</summary>
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[Test]
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public void IntegersCanBeReinterpretedAsFloats() {
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Assert.AreEqual(
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12345.0f,
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FloatHelper.ReinterpretAsFloat(FloatHelper.ReinterpretAsInt(12345.0f)),
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"Number hasn't changed after mirrored reinterpretation"
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);
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}
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/// <summary>Tests the long reinterpretation functions</summary>
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[Test]
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public void LongsCanBeReinterpretedAsDoubles() {
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Assert.AreEqual(
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12345.67890,
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FloatHelper.ReinterpretAsDouble(FloatHelper.ReinterpretAsLong(12345.67890)),
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"Number hasn't changed after mirrored reinterpretation"
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);
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}
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/// <summary>Tests the floating point reinterpretation functions</summary>
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[Test]
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public void FloatsCanBeReinterpretedAsIntegers() {
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Assert.AreEqual(
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12345,
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FloatHelper.ReinterpretAsInt(FloatHelper.ReinterpretAsFloat(12345)),
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"Number hasn't changed after mirrored reinterpretation"
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);
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}
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/// <summary>
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/// Verifies that the IsZero() method can distinguish zero from very small values
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/// </summary>
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[Test]
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public void CanDetermineIfFloatIsZero() {
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Assert.IsTrue(FloatHelper.IsZero(FloatHelper.PositiveZeroFloat));
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Assert.IsTrue(FloatHelper.IsZero(FloatHelper.NegativeZeroFloat));
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Assert.IsFalse(FloatHelper.IsZero(1.401298E-45f));
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Assert.IsFalse(FloatHelper.IsZero(-1.401298E-45f));
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}
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/// <summary>
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/// Verifies that the IsZero() method can distinguish zero from very small values
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/// </summary>
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[Test]
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public void CanDetermineIfDoubleIsZero() {
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Assert.IsTrue(FloatHelper.IsZero(FloatHelper.PositiveZeroDouble));
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Assert.IsTrue(FloatHelper.IsZero(FloatHelper.NegativeZeroDouble));
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Assert.IsFalse(FloatHelper.IsZero(4.94065645841247E-324));
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Assert.IsFalse(FloatHelper.IsZero(-4.94065645841247E-324));
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}
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/// <summary>
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/// Tests the double prevision floating point reinterpretation functions
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/// </summary>
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[Test]
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public void DoublesCanBeReinterpretedAsLongs() {
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Assert.AreEqual(
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1234567890,
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FloatHelper.ReinterpretAsLong(FloatHelper.ReinterpretAsDouble(1234567890)),
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"Number hasn't changed after mirrored reinterpretation"
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);
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}
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/// <summary>
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/// Verifies that two denormalized floats can be compared in ulps
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/// </summary>
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[Test]
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public void DenormalizedFloatsCanBeCompared() {
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float zero = 0.0f;
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float zeroPlusOneUlp = FloatHelper.ReinterpretAsFloat(
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FloatHelper.ReinterpretAsInt(zero) + 1
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);
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float zeroMinusOneUlp = -zeroPlusOneUlp;
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// Across zero
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Assert.IsFalse(FloatHelper.AreAlmostEqual(zeroMinusOneUlp, zeroPlusOneUlp, 1));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(zeroPlusOneUlp, zeroMinusOneUlp, 2));
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// Against zero
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Assert.IsFalse(FloatHelper.AreAlmostEqual(zero, zeroPlusOneUlp, 0));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(zero, zeroPlusOneUlp, 1));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(zero, zeroMinusOneUlp, 0));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(zero, zeroMinusOneUlp, 1));
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}
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/// <summary>
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/// Verifies that the negative floating point zero is within one ulp of the positive
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/// floating point zero and vice versa
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/// </summary>
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[Test]
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public void NegativeZeroFloatEqualsPositiveZero() {
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(
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FloatHelper.NegativeZeroFloat, FloatHelper.PositiveZeroFloat, 0
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)
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);
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(
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FloatHelper.PositiveZeroFloat, FloatHelper.NegativeZeroFloat, 0
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)
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);
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}
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/// <summary>Verifies that floats can be compared across the zero boundary</summary>
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[Test]
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public void FloatsCanBeComparedAcrossZeroInUlps() {
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float tenUlps = float.Epsilon * 10.0f;
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Assert.IsTrue(FloatHelper.AreAlmostEqual(-tenUlps, tenUlps, 20));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(tenUlps, -tenUlps, 20));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(-tenUlps, tenUlps, 19));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(-tenUlps, 0, 10));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(0, -tenUlps, 10));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(-tenUlps, 0, 9));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(0, tenUlps, 10));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(tenUlps, 0, 10));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(0, tenUlps, 9));
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}
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/// <summary>
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/// Verifies that two denormalized doubles can be compared in ulps
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/// </summary>
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[Test]
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public void DenormalizedDoublesCanBeCompared() {
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double zero = 0.0;
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double zeroPlusOneUlp = FloatHelper.ReinterpretAsDouble(
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FloatHelper.ReinterpretAsLong(zero) + 1
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);
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double zeroMinusOneUlp = -zeroPlusOneUlp;
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// Across zero
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Assert.IsFalse(FloatHelper.AreAlmostEqual(zeroMinusOneUlp, zeroPlusOneUlp, 1));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(zeroPlusOneUlp, zeroMinusOneUlp, 2));
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// Against zero
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Assert.IsFalse(FloatHelper.AreAlmostEqual(zero, zeroPlusOneUlp, 0));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(zero, zeroPlusOneUlp, 1));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(zero, zeroMinusOneUlp, 0));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(zero, zeroMinusOneUlp, 1));
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}
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/// <summary>
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/// Verifies that the negative double precision floating point zero is within one ulp
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/// of the positive double precision floating point zero and vice versa
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/// </summary>
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[Test]
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public void NegativeZeroDoubleEqualsPositiveZero() {
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(
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FloatHelper.NegativeZeroDouble, FloatHelper.NegativeZeroDouble, 0
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)
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);
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Assert.IsTrue(
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FloatHelper.AreAlmostEqual(
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FloatHelper.NegativeZeroDouble, FloatHelper.NegativeZeroDouble, 0
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)
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);
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}
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/// <summary>Verifies that doubles can be compared across the zero boundary</summary>
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[Test]
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public void DoublesCanBeComparedAcrossZeroInUlps() {
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double tenUlps = double.Epsilon * 10.0;
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Assert.IsTrue(FloatHelper.AreAlmostEqual(-tenUlps, tenUlps, 20));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(tenUlps, -tenUlps, 20));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(-tenUlps, tenUlps, 19));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(-tenUlps, 0, 10));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(0, -tenUlps, 10));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(-tenUlps, 0, 9));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(0, tenUlps, 10));
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Assert.IsTrue(FloatHelper.AreAlmostEqual(tenUlps, 0, 10));
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Assert.IsFalse(FloatHelper.AreAlmostEqual(0, tenUlps, 9));
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}
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}
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} // namespace Nuclex.Support
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#endif // UNITTEST
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