From 92d6193360f5db5e609c0a98a6e9f169181c12a6 Mon Sep 17 00:00:00 2001
From: Hamlet Tanyavong <34531738+HamletTanyavong@users.noreply.github.com>
Date: Mon, 6 Nov 2023 15:29:50 -0600
Subject: [PATCH] Add modulo operation

---
 src/Mathematics.NET/Core/IReal.cs             |  1 +
 .../Core/Operations/IModuloOperation.cs       | 37 +++++++++++++++++++
 src/Mathematics.NET/Core/Rational.cs          | 11 ++++++
 src/Mathematics.NET/Core/Real.cs              |  1 +
 4 files changed, 50 insertions(+)
 create mode 100644 src/Mathematics.NET/Core/Operations/IModuloOperation.cs

diff --git a/src/Mathematics.NET/Core/IReal.cs b/src/Mathematics.NET/Core/IReal.cs
index e48ec194..3b9a1bbb 100644
--- a/src/Mathematics.NET/Core/IReal.cs
+++ b/src/Mathematics.NET/Core/IReal.cs
@@ -35,6 +35,7 @@ namespace Mathematics.NET.Core;
 /// <typeparam name="T">A type that implements the interface</typeparam>
 public interface IReal<T>
     : IComplex<T>,
+      IModuloOperation<T, T>,
       IInequalityRelations<T, bool>,
       IDecrementOperation<T>,
       IIncrementOperation<T>,
diff --git a/src/Mathematics.NET/Core/Operations/IModuloOperation.cs b/src/Mathematics.NET/Core/Operations/IModuloOperation.cs
new file mode 100644
index 00000000..bc11ec15
--- /dev/null
+++ b/src/Mathematics.NET/Core/Operations/IModuloOperation.cs
@@ -0,0 +1,37 @@
+// <copyright file="IModuloOperation.cs" company="Mathematics.NET">
+// Mathematics.NET
+// https://github.com/HamletTanyavong/Mathematics.NET
+//
+// MIT License
+//
+// Copyright (c) 2023 Hamlet Tanyavong
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+// </copyright>
+
+namespace Mathematics.NET.Core.Operations;
+
+/// <summary>Defines a mechanism for computing modulos</summary>
+/// <typeparam name="TInput">The input type</typeparam>
+/// <typeparam name="TOutput">The output type</typeparam>
+public interface IModuloOperation<TInput, TOutput>
+    where TInput : IModuloOperation<TInput, TOutput>
+{
+    static abstract TOutput operator %(TInput left, TInput right);
+}
diff --git a/src/Mathematics.NET/Core/Rational.cs b/src/Mathematics.NET/Core/Rational.cs
index 2250c7e0..ebe22264 100644
--- a/src/Mathematics.NET/Core/Rational.cs
+++ b/src/Mathematics.NET/Core/Rational.cs
@@ -151,6 +151,17 @@ public Rational(T p, T q)
         return new(num / gcd, den / gcd);
     }
 
+    public static Rational<T> operator %(Rational<T> x, Rational<T> y)
+    {
+        if (y._denominator == T.Zero)
+        {
+            return NaN;
+        }
+
+        var q = x / y;
+        return T.DivRem(q._numerator, q._denominator).Remainder;
+    }
+
     //
     // Equality
     //
diff --git a/src/Mathematics.NET/Core/Real.cs b/src/Mathematics.NET/Core/Real.cs
index 2ec49d84..8865dfbe 100644
--- a/src/Mathematics.NET/Core/Real.cs
+++ b/src/Mathematics.NET/Core/Real.cs
@@ -148,6 +148,7 @@ public Real(double real)
     public static Real operator -(Real left, Real right) => left._value - right._value;
     public static Real operator *(Real left, Real right) => left._value * right._value;
     public static Real operator /(Real left, Real right) => left._value / right._value;
+    public static Real operator %(Real left, Real right) => left._value % right._value;
 
     //
     // Equality