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RatMath Library

JavaScript library for exact rational arithmetic using BigInt

Key Features

๐ŸŽฏ Exact Arithmetic

No floating-point errors. Every calculation maintains perfect precision using BigInt internally. 

// JavaScript floats
0.1 + 0.2 === 0.3  // false!

// RatMath
R`0.1 + 0.2`.equals(R`0.3`)  // true!

๐Ÿ“Š Interval Arithmetic

Built-in support for interval calculations, perfect for uncertainty analysis. 

// Create intervals
const a = R`1:2`      // [1, 2]
const b = R`0.5:1.5`  // [0.5, 1.5]

// Operations preserve bounds
R`1:2 + 0.5:1.5`  // [1.5, 3.5]

๐Ÿ”ข Type System

Smart type promotion: Integer โ†’ Rational โ†’ RationalInterval as needed. 

R`5 + 7`        // Integer(12)
R`5 / 2`        // Rational(5/2)
R`5 + 1:2`      // RationalInterval([6, 7])

๐ŸŽจ Rich Notation

Support for mixed numbers, repeating decimals, continued fractions, and more. 

R`2..1/3`    // Mixed: 2 and 1/3
R`0.#3`      // Repeating: 0.333... = 1/3
R`3.~7~15~1` // Continued fraction = 355/113

Interactive Examples

Basic Arithmetic

Repeating Decimals

Interval Operations

Continued Fractions

Code Playground

Try the RatMath API directly in your browser. Press Ctrl+Enter (or Cmd+Enter) to run code:

API Quick Reference

Creating Numbers

R\`1/2\`         // Rational
R\`42\`          // Integer
R\`1:2\`         // Interval
F\`3/4\`         // Fraction (no reduction)

Operations

.add(other)
.subtract(other)
.multiply(other)
.divide(other)
.pow(n)

Comparisons

.equals(other)
.lessThan(other)
.greaterThan(other)
.lessThanOrEqual(other)
.greaterThanOrEqual(other)

Conversions

.toString()
.toDecimal(limit)
.toMixed()
.toContinuedFraction()
.toScientific(precision)

Installation

NPM

npm install @ratmath/core

Bun

bun add @ratmath/core

Browser (ES Modules)

<script type="module">
  import { R, F } from './ratmath.js';
  // Your code here
</script>

Basic Usage

import { R, Parser } from '@ratmath/core';

// Using template literals with expressions
const sum = R\`1/3 + 2/3\`;  // Rational(1)

// Or using method calls
const third = R\`1/3\`;
const twoThirds = R\`2/3\`;
const sum2 = third.add(twoThirds);  // Rational(1)

// Using Parser directly
const expr = Parser.parse("1/2 + 1/3");  // Rational(5/6)

// Working with intervals
const measurement = R\`5.2[+-0.05]\`;  // [5.15, 5.25]