Rational 2.0.0

RationalSharp

RationalSharp is a .NET library for exact rational number arithmetic in C#.

It provides a Rational type (ShInUeXx.Numerics.Rational) backed by BigInteger, with support for:

• exact fraction arithmetic (1/3 + 1/6 == 1/2)
• parsing and formatting ("3 1/2", "1.25e2", localized decimal separator)
• special values (NaN, +Infinity, -Infinity)
• .NET generic math (INumber<Rational>)

Requirements

• .NET 10.0 (net10.0)

Installation

dotnet add package Rational

Quick Start

using ShInUeXx.Numerics;

var a = new Rational(1, 3);
var b = new Rational(1, 6);
var sum = a + b;              // 1/2

Console.WriteLine(sum);       // "1/2"
Console.WriteLine(sum == Rational.Half); // True

Creating Values

using ShInUeXx.Numerics;
using System.Numerics;

var x = new Rational(7, 5);
var y = new Rational(new BigInteger(42));

var fromDouble = Rational.From(0.125);    // exact IEEE -> rational conversion
var fromDecimal = Rational.From(12.34m);  // exact decimal -> rational conversion

Available predefined values include:

• Rational.Zero
• Rational.One
• Rational.Half
• Rational.NaN
• Rational.PositiveInfinity
• Rational.NegativeInfinity

Parsing

Supported formats include:

• integer: "123"
• fraction: "2/3"
• mixed fraction: "3 1/2"
• decimal / scientific: "1.25", "1.25e2"

using ShInUeXx.Numerics;
using System.Globalization;

var a = Rational.Parse("2/3");
var b = Rational.Parse("3 1/2");
var c = Rational.Parse("1.25e2"); // 125

var pl = CultureInfo.GetCultureInfo("pl-PL");
var d = Rational.Parse("1,5", NumberStyles.AllowDecimalPoint, pl); // 3/2

Formatting

Rational supports ToString(format, provider) and TryFormat(...).

Format specifiers:

• F (or empty): fraction form n/d
• D / D{precision}: decimal form (D2 → 2 fractional digits)
• W: whole + fraction form (1 1/2)

using ShInUeXx.Numerics;
using System.Globalization;

var x = new Rational(-1, 2);

Console.WriteLine(x.ToString("F", CultureInfo.InvariantCulture));  // -1/2
Console.WriteLine(x.ToString("D2", CultureInfo.InvariantCulture)); // -0.50
Console.WriteLine(x.ToString("W", CultureInfo.InvariantCulture));  // -0 1/2

Math Helpers

The library includes helpers such as:

• Rational.Abs
• Rational.Truncate
• Rational.Floor
• Rational.Ceiling
• Rational.Round / Rational.Round(..., MidpointRounding)
• Rational.Pow
• Rational.Log
• Rational.Modulo (same semantics as %, truncate-toward-zero quotient)
• Rational.ModuloEuclidean (Euclidean modulo)

var r = new Rational(-1, 2);

var trunc = Rational.Truncate(r);         // 0
var floor = Rational.Floor(r);            // -1
var rem = new Rational(-1, 2) % new Rational(1, 3);          // -1/6
var euclid = Rational.ModuloEuclidean(new Rational(-1, 2), new Rational(1, 3)); // 1/6

Continued Fractions

var r = Rational.FromContinuedForm([1, 2, 2]); // 7/5
var terms = r.ToContinuedForm<int>().ToArray(); // [1, 2, 2]

Notes:

• FromContinuedForm(...) requires at least one term.
• ToContinuedForm(...) is defined for finite values only.

Special Values

Rational supports non-finite values using the internal representations:

• NaN = 0/0
• +Infinity = 1/0
• -Infinity = -1/0

These values are propagated consistently across parsing/conversion/formatting where applicable.

Generic Math

Rational implements INumber<Rational>, so it can be used in generic numeric code in modern .NET.

static T AddOne<T>(T value) where T : INumber<T>
    => value + T.One;

var r = AddOne(new Rational(2, 3)); // 5/3

License

MIT (see LICENSE)