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Added new numerics features, including SetScale extension methods for System.Decimal, and GenericMath.Pow10.
feature/decimal-set-scale
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6 files changed

+349
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‎Directory.Build.props‎

Lines changed: 3 additions & 3 deletions
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@@ -1,5 +1,8 @@
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<Project>
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<PropertyGroup>
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<Version>12.1.0</Version>
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<PackageVersion>12.1.0</PackageVersion>
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<AssemblyVersion>12.1.0</AssemblyVersion>
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<TargetFrameworks>net8.0;net9.0</TargetFrameworks>
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<LangVersion>13</LangVersion>
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<Nullable>enable</Nullable>
@@ -8,8 +11,5 @@
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<NeutralLanguage>en</NeutralLanguage>
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<Copyright>Copyright © ONIXLabs 2020</Copyright>
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<RepositoryUrl>https://github.com/onix-labs/onixlabs-dotnet</RepositoryUrl>
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<Version>12.0.0</Version>
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<PackageVersion>12.0.0</PackageVersion>
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<AssemblyVersion>12.0.0</AssemblyVersion>
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</PropertyGroup>
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</Project>

‎OnixLabs.Numerics.UnitTests/GenericMathPow10Tests.cs‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,94 @@
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// Copyright 2020-2025 ONIXLabs
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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using System;
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using Xunit;
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namespace OnixLabs.Numerics.UnitTests;
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public sealed class GenericMathPow10Tests
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{
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[Theory(DisplayName = "GenericMath.Pow10 should produce the expected result (Int32)")]
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[InlineData(0, 1)]
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[InlineData(1, 10)]
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[InlineData(2, 100)]
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[InlineData(3, 1000)]
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[InlineData(4, 10000)]
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[InlineData(5, 100000)]
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[InlineData(6, 1000000)]
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[InlineData(9, 1000000000)]
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public void GenericMathPow10ShouldProduceExpectedResultInt32(int exponent, int expected)
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{
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// Given / When
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int result = GenericMath.Pow10<int>(exponent);
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// Then
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Assert.Equal(expected, result);
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}
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[Theory(DisplayName = "GenericMath.Pow10 should produce the expected result (Int64)")]
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[InlineData(0, 1L)]
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[InlineData(1, 10L)]
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[InlineData(2, 100L)]
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[InlineData(10, 10000000000L)]
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[InlineData(15, 1000000000000000L)]
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public void GenericMathPow10ShouldProduceExpectedResultInt64(int exponent, long expected)
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{
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// Given / When
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long result = GenericMath.Pow10<long>(exponent);
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// Then
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Assert.Equal(expected, result);
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}
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[Theory(DisplayName = "GenericMath.Pow10 should produce the expected result (Double)")]
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[InlineData(0, 1.0)]
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[InlineData(3, 1000.0)]
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[InlineData(6, 1e6)]
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[InlineData(9, 1e9)]
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[InlineData(15, 1e15)]
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public void GenericMathPow10ShouldProduceExpectedResultDouble(int exponent, double expected)
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{
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// Given / When
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double result = GenericMath.Pow10<double>(exponent);
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// Then
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Assert.Equal(expected, result, precision: 10);
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}
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[Theory(DisplayName = "GenericMath.Pow10 should produce the expected result (Decimal)")]
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[InlineData(0, "1")]
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[InlineData(1, "10")]
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[InlineData(5, "100000")]
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[InlineData(10, "10000000000")]
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public void GenericMathPow10ShouldProduceExpectedResultDecimal(int exponent, string expectedStr)
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{
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// Given / When
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decimal expected = decimal.Parse(expectedStr);
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decimal result = GenericMath.Pow10<decimal>(exponent);
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// Then
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Assert.Equal(expected, result);
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}
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[Fact(DisplayName = "GenericMath.Pow10 should throw ArgumentException when the exponent is negative.")]
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public void GenericMathPow10ShouldThrowArgumentExceptionWhenExponentNegative()
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{
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// Given / When
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Exception exception = Assert.Throws<ArgumentException>(() => GenericMath.Pow10<int>(-1));
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// Then
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Assert.Contains("Exponent must be greater", exception.Message);
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}
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}

‎OnixLabs.Numerics.UnitTests/NumericsExtensionsTests.cs‎

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Original file line numberDiff line numberDiff line change
@@ -80,6 +80,107 @@ public void DecimalGetUnscaledValueShouldProduceExpectedResultValueAndScale(int
8080
Assert.Equal(expected, actual);
8181
}
8282

83+
[Theory(DisplayName = "Decimal.SetScale should preserve or pad when scale is less or equal")]
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[InlineData("123.0", 2, "123.00")]
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[InlineData("123.00", 2, "123.00")]
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[InlineData("123.000", 2, "123.00")]
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[InlineData("0.0", 2, "0.00")]
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[InlineData("123.12", 2, "123.12")]
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public void DecimalSetScaleShouldPreserveOrPadWhenScaleIsLessOrEqual(string inputStr, int scale, string expectedStr)
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{
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// Given
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decimal input = decimal.Parse(inputStr);
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decimal expected = decimal.Parse(expectedStr);
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// When
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decimal result = input.SetScale(scale);
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// Then
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Assert.Equal(expected, result);
100+
}
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[Theory(DisplayName = "Decimal.SetScale should truncate when no precision loss")]
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[InlineData("123.1200", 2, "123.12")]
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[InlineData("0.1000", 1, "0.1")]
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[InlineData("999.0000", 3, "999.000")]
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public void DecimalSetScaleShouldTruncateWhenNoPrecisionLoss(string inputStr, int scale, string expectedStr)
107+
{
108+
// Given
109+
decimal input = decimal.Parse(inputStr);
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decimal expected = decimal.Parse(expectedStr);
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// When
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decimal result = input.SetScale(scale);
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// Then
116+
Assert.Equal(expected, result);
117+
}
118+
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[Theory(DisplayName = "Decimal.SetScale should throw when truncation would lose precision")]
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[InlineData("123.456", 2)]
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[InlineData("1.001", 2)]
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[InlineData("0.123456789", 5)]
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public void DecimalSetScaleShouldThrowWhenTruncationWouldLosePrecision(string inputStr, int scale)
124+
{
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// Given
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decimal input = decimal.Parse(inputStr);
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// When / Then
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Assert.Throws<InvalidOperationException>(() => input.SetScale(scale));
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}
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[Theory(DisplayName = "Decimal.SetScale(rounding) should apply correct rounding")]
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[InlineData("123.456", 2, MidpointRounding.AwayFromZero, "123.46")]
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[InlineData("123.454", 2, MidpointRounding.AwayFromZero, "123.45")]
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[InlineData("123.455", 2, MidpointRounding.ToZero, "123.45")]
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[InlineData("123.455", 2, MidpointRounding.ToEven, "123.46")]
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[InlineData("0.125", 2, MidpointRounding.ToEven, "0.12")]
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[InlineData("0.135", 2, MidpointRounding.ToEven, "0.14")]
139+
public void DecimalSetScaleWithRoundingShouldApplyCorrectRounding(string inputStr, int scale, MidpointRounding mode, string expectedStr)
140+
{
141+
// Given
142+
decimal input = decimal.Parse(inputStr);
143+
decimal expected = decimal.Parse(expectedStr);
144+
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// When
146+
decimal result = input.SetScale(scale, mode);
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148+
// Then
149+
Assert.Equal(expected, result);
150+
}
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[Theory(DisplayName = "Decimal.SetScale(rounding) should truncate when no precision loss")]
153+
[InlineData("123.0000", 2, MidpointRounding.AwayFromZero, "123.00")]
154+
[InlineData("1.000", 1, MidpointRounding.ToEven, "1.0")]
155+
public void DecimalSetScaleWithRoundingShouldTruncateWhenNoPrecisionLoss(string inputStr, int scale, MidpointRounding mode, string expectedStr)
156+
{
157+
// Given
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decimal input = decimal.Parse(inputStr);
159+
decimal expected = decimal.Parse(expectedStr);
160+
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// When
162+
decimal result = input.SetScale(scale, mode);
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// Then
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Assert.Equal(expected, result);
166+
}
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[Fact(DisplayName = "Decimal.SetScale should throw when scale is negative")]
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public void DecimalSetScaleShouldThrowWhenScaleIsNegative()
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{
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// Given / When / Then
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Exception exception = Assert.Throws<ArgumentException>(() => 123.45m.SetScale(-1));
173+
Assert.Contains("Scale must be greater than, or equal to zero.", exception.Message);
174+
}
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[Fact(DisplayName = "Decimal.SetScale(rounding) should throw when scale is negative")]
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public void DecimalSetScaleWithRoundingShouldThrowWhenScaleIsNegative()
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{
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// Given / When / Then
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Exception exception = Assert.Throws<ArgumentException>(() => 123.45m.SetScale(-1, MidpointRounding.AwayFromZero));
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Assert.Contains("Scale must be greater than, or equal to zero.", exception.Message);
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}
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[Theory(DisplayName = "INumber<T>.IsBetween should produce the expected result")]
84185
[InlineData(0, 0, 0, true)]
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[InlineData(0, 0, 1, true)]

‎OnixLabs.Numerics/GenericMath.cs‎

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Original file line numberDiff line numberDiff line change
@@ -12,6 +12,7 @@
1212
// See the License for the specific language governing permissions and
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// limitations under the License.
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15+
using System;
1516
using System.Globalization;
1617
using System.Numerics;
1718

@@ -41,7 +42,7 @@ public static BigInteger Factorial<T>(T value) where T : IBinaryInteger<T>
4142
{
4243
Require(value >= T.Zero, "Value must be greater than or equal to zero.");
4344

44-
if(value <= T.One) return BigInteger.One;
45+
if (value <= T.One) return BigInteger.One;
4546

4647
BigInteger result = BigInteger.One;
4748

@@ -71,4 +72,33 @@ public static int IntegerLength<T>(T value) where T : INumberBase<T>
7172
/// <typeparam name="T">The underlying <see cref="INumber{TSelf}"/> type.</typeparam>
7273
/// <returns>Returns the minimum and maximum values from the specified left-hand and right-hand values.</returns>
7374
public static (T Min, T Max) MinMax<T>(T left, T right) where T : INumber<T> => (T.Min(left, right), T.Max(left, right));
75+
76+
/// <summary>
77+
/// Computes 10 raised to the power of a non-negative integer exponent using exponentiation by squaring, for any numeric type implementing <see cref="INumber{T}"/>.
78+
/// </summary>
79+
/// <typeparam name="T">The numeric type. Must implement <see cref="INumber{T}"/>.</typeparam>
80+
/// <param name="exponent">The exponent to raise 10 to. Must be greater than or equal to zero.</param>
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/// <returns>A value of type <typeparamref name="T"/> equal to 10 raised to the power of <paramref name="exponent"/>.</returns>
82+
/// <exception cref="ArgumentException"> if <paramref name="exponent"/> is less than zero.</exception>
83+
public static T Pow10<T>(int exponent) where T : INumber<T>
84+
{
85+
Require(exponent >= 0, "Exponent must be greater than, or equal to zero.", nameof(exponent));
86+
87+
if (exponent == 0)
88+
return T.One;
89+
90+
T result = T.One;
91+
T baseValue = T.CreateChecked(10);
92+
93+
while (exponent > 0)
94+
{
95+
if ((exponent & 1) == 1)
96+
result *= baseValue;
97+
98+
baseValue *= baseValue;
99+
exponent >>= 1;
100+
}
101+
102+
return result;
103+
}
74104
}

‎OnixLabs.Numerics/NumericsExtensions.cs‎

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Original file line numberDiff line numberDiff line change
@@ -51,6 +51,73 @@ public static BigInteger GetUnscaledValue(this decimal value)
5151
return decimal.IsPositive(value) ? result : -result;
5252
}
5353

54+
/// <summary>
55+
/// Sets the scale (number of digits after the decimal point) of the current <see cref="decimal"/> value.
56+
/// <remarks>
57+
/// If the scale of the current <see cref="decimal"/> value is less than the specified scale, then the scale will be padded with zeroes.
58+
/// If the scale of the current <see cref="decimal"/> value is greater that the specified scale, then the scale will be truncated,
59+
/// provided that there is no loss of precision; otherwise, <see cref="InvalidOperationException"/> will be thrown.
60+
/// </remarks>
61+
/// </summary>
62+
/// <param name="value">The decimal value to adjust.</param>
63+
/// <param name="scale">The desired, non-negative scale.</param>
64+
/// <returns>A new <see cref="decimal"/> with the exact specified scale.</returns>
65+
/// <exception cref="InvalidOperationException"> if reducing the scale would result in a loss of precision.</exception>
66+
/// <exception cref="ArgumentException"> if <paramref name="scale"/> is negative.</exception>
67+
public static decimal SetScale(this decimal value, int scale)
68+
{
69+
Require(scale >= 0, "Scale must be greater than, or equal to zero.", nameof(scale));
70+
71+
if (value.Scale == scale)
72+
return value;
73+
74+
if (value.Scale < scale)
75+
{
76+
decimal factor = GenericMath.Pow10<decimal>(scale - value.Scale);
77+
return value * factor / factor;
78+
}
79+
80+
decimal pow10 = GenericMath.Pow10<decimal>(scale);
81+
decimal truncated = Math.Truncate(value * pow10) / pow10;
82+
83+
if (value == truncated)
84+
return truncated;
85+
86+
throw new InvalidOperationException($"Cannot reduce scale without losing precision: {value}");
87+
}
88+
89+
/// <summary>
90+
/// Sets the scale (number of digits after the decimal point) of the current <see cref="decimal"/> value.
91+
/// <remarks>
92+
/// If the scale of the current <see cref="decimal"/> value is less than the specified scale, then the scale will be padded with zeroes.
93+
/// If the scale of the current <see cref="decimal"/> value is greater that the specified scale, then the scale will be truncated,
94+
/// provided that there is no loss of precision; otherwise, the value is rounded using the specified <see cref="MidpointRounding"/> mode.
95+
/// </remarks>
96+
/// </summary>
97+
/// <param name="value">The decimal value to adjust.</param>
98+
/// <param name="scale">The desired scale (number of decimal digits). Must be non-negative.</param>
99+
/// <param name="mode">The rounding strategy to apply if the scale must be reduced with precision loss.</param>
100+
/// <returns>A new <see cref="decimal"/> with the exact specified scale.</returns>
101+
/// <exception cref="ArgumentException"> if <paramref name="scale"/> is negative.</exception>
102+
public static decimal SetScale(this decimal value, int scale, MidpointRounding mode)
103+
{
104+
Require(scale >= 0, "Scale must be greater than, or equal to zero.", nameof(scale));
105+
106+
if (value.Scale == scale)
107+
return value;
108+
109+
if (value.Scale < scale)
110+
{
111+
decimal factor = GenericMath.Pow10<decimal>(scale - value.Scale);
112+
return value * factor / factor;
113+
}
114+
115+
decimal pow10 = GenericMath.Pow10<decimal>(scale);
116+
decimal truncated = Math.Truncate(value * pow10) / pow10;
117+
118+
return value == truncated ? truncated : Math.Round(value, scale, mode);
119+
}
120+
54121
/// <summary>
55122
/// Gets the current value as an unscaled integer.
56123
/// </summary>

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