Add absolute value algorithm (#462)

Algorithms.Tests/Numeric/AbsTests.cs

@@ -0,0 +1,67 @@
+using System;
+using System.Numerics;
+using Algorithms.Numeric;
+using NUnit.Framework;
+
+namespace Algorithms.Tests.Numeric;
+
+public static class AbsTests
+{
+    [TestCase(0, 0)]
+    [TestCase(34, 34)]
+    [TestCase(-100000000000.0d, 100000000000.0d)]
+    [TestCase(-3, 3)]
+    [TestCase(-3.1443123d, 3.1443123d)]
+    public static void GetsAbsVal<T>(T inputNum, T expected) where T : INumber<T>
+    {
+        // Act
+        var result = Abs.AbsVal(inputNum);
+
+        // Assert
+        Assert.That(result, Is.EqualTo(expected));
+    }
+
+    [TestCase(new[] { -3, -1, 2, -11 }, -11)]
+    [TestCase(new[] { 0, 5, 1, 11 }, 11)]
+    [TestCase(new[] { 3.0, -10.0, -2.0 }, -10.0d)]
+    public static void GetAbsMax<T>(T[] inputNums, T expected) where T : INumber<T>
+    {
+        // Act
+        var result = Abs.AbsMax(inputNums);
+
+        // Assert
+        Assert.That(result, Is.EqualTo(expected));
+    }
+
+    [Test]
+    public static void AbsMaxThrowsArgumentException()
+    {
+        // Arrange
+        var inputNums = Array.Empty<int>();
+
+        // Assert
+        Assert.Throws<ArgumentException>(() => Abs.AbsMax(inputNums));
+    }
+
+    [TestCase(new[] { -3, -1, 2, -11 }, -1)]
+    [TestCase(new[] { -3, -5, 1, -11 }, 1)]
+    [TestCase(new[] { 0, 5, 1, 11 }, 0)]
+    public static void GetAbsMin<T>(T[] inputNums, T expected) where T : INumber<T>
+    {
+        // Act
+        var result = Abs.AbsMin(inputNums);
+
+        // Assert
+        Assert.That(result, Is.EqualTo(expected));
+    }
+
+    [Test]
+    public static void AbsMinThrowsArgumentException()
+    {
+        // Arrange
+        var inputNums = Array.Empty<int>();
+
+        // Assert
+        Assert.Throws<ArgumentException>(() => Abs.AbsMin(inputNums));
+    }
+}

Algorithms/Numeric/Abs.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Numerics;
+
+namespace Algorithms.Numeric;
+
+/// <summary>
+///     Find the absolute value of a number.
+/// </summary>
+public static class Abs
+{
+    /// <summary>
+    ///    Returns the absolute value of a number.
+    /// </summary>
+    /// <typeparam name="T">Type of number.</typeparam>
+    /// <param name="inputNum">Number to find the absolute value of.</param>
+    /// <returns>Absolute value of the number.</returns>
+    public static T AbsVal<T>(T inputNum) where T : INumber<T>
+    {
+        return T.IsNegative(inputNum) ? -inputNum : inputNum;
+    }
+
+    /// <summary>
+    ///   Returns the number with the smallest absolute value on the input array.
+    /// </summary>
+    /// <typeparam name="T">Type of number.</typeparam>
+    /// <param name="inputNums">Array of numbers to find the smallest absolute.</param>
+    /// <returns>Smallest absolute number.</returns>
+    public static T AbsMin<T>(T[] inputNums) where T : INumber<T>
+    {
+        if (inputNums.Length == 0)
+        {
+            throw new ArgumentException("Array is empty.");
+        }
+
+        var min = inputNums[0];
+        for (var index = 1; index < inputNums.Length; index++)
+        {
+            var current = inputNums[index];
+            if (AbsVal(current).CompareTo(AbsVal(min)) < 0)
+            {
+                min = current;
+            }
+        }
+
+        return min;
+    }
+
+    /// <summary>
+    ///  Returns the number with the largest absolute value on the input array.
+    /// </summary>
+    /// <typeparam name="T">Type of number.</typeparam>
+    /// <param name="inputNums">Array of numbers to find the largest absolute.</param>
+    /// <returns>Largest absolute number.</returns>
+    public static T AbsMax<T>(T[] inputNums) where T : INumber<T>
+    {
+        if (inputNums.Length == 0)
+        {
+            throw new ArgumentException("Array is empty.");
+        }
+
+        var max = inputNums[0];
+        for (var index = 1; index < inputNums.Length; index++)
+        {
+            var current = inputNums[index];
+            if (AbsVal(current).CompareTo(AbsVal(max)) > 0)
+            {
+                max = current;
+            }
+        }
+
+        return max;
+    }
+}

README.md

@@ -66,6 +66,7 @@ find more than one implementation for the same objective but using different alg
     * [Extended Euclidean Algorithm](./Algorithms/ModularArithmetic/ExtendedEuclideanAlgorithm.cs)
     * [Modular Multiplicative Inverse](./Algorithms/ModularArithmetic/ModularMultiplicativeInverse.cs)
   * [Numeric](./Algorithms/Numeric)
+    * [Absolute](./Algorithms/Numeric/Abs.cs) 
     * [Aliquot Sum Calculator](./Algorithms/Numeric/AliquotSumCalculator.cs)
     * [Amicable Numbers Checker](./Algorithms/Numeric/AmicableNumbersChecker.cs)
     * [Decomposition](./Algorithms/Numeric/Decomposition)