mathjs/examples/fractions.js

// Fractions

// load math.js (using node.js)
const { create, all } = require('..')

// configure the default type of numbers as Fractions
const config = {
  // Default type of number
  // Available options: 'number' (default), 'BigNumber', or 'Fraction'
  number: 'Fraction'
}

// create a mathjs instance with everything included
const math = create(all, config)

console.log('basic usage')
printRatio(math.fraction(0.125)) // Fraction, 1/8
printRatio(math.fraction(0.32)) // Fraction, 8/25
printRatio(math.fraction('1/3')) // Fraction, 1/3
printRatio(math.fraction('0.(3)')) // Fraction, 1/3
printRatio(math.fraction(2, 3)) // Fraction, 2/3
printRatio(math.fraction('0.(285714)')) // Fraction, 2/7
console.log()

console.log('round-off errors with numbers')
print(math.add(0.1, 0.2)) // number, 0.30000000000000004
print(math.divide(0.3, 0.2)) // number, 1.4999999999999998
console.log()

console.log('no round-off errors with fractions :)')
print(math.add(math.fraction(0.1), math.fraction(0.2))) // Fraction, 0.3
print(math.divide(math.fraction(0.3), math.fraction(0.2))) // Fraction, 1.5
console.log()

console.log('represent an infinite number of repeating digits')
print(math.fraction('1/3')) // Fraction, 0.(3)
print(math.fraction('2/7')) // Fraction, 0.(285714)
print(math.fraction('23/11')) // Fraction, 2.(09)
console.log()

// one can work conveniently with fractions using the expression parser.
// note though that Fractions are only supported by basic arithmetic functions
console.log('use fractions in the expression parser')
printRatio(math.evaluate('0.1 + 0.2')) // Fraction,  3/10
printRatio(math.evaluate('0.3 / 0.2')) // Fraction,  3/2
printRatio(math.evaluate('23 / 11')) // Fraction, 23/11
console.log()

// output formatting
console.log('output formatting of fractions')
const a = math.fraction('2/3')
console.log(math.format(a)) // Fraction,  2/3
console.log(math.format(a, { fraction: 'ratio' })) // Fraction,  2/3
console.log(math.format(a, { fraction: 'decimal' })) // Fraction,  0.(6)
console.log(a.toString()) // Fraction,  0.(6)
console.log()

/**
 * Helper function to output a value in the console.
 * Fractions will be formatted as ratio, like '1/3'.
 * @param {*} value
 */
function printRatio (value) {
  console.log(math.format(value, { fraction: 'ratio' }))
}

/**
 * Helper function to output a value in the console.
 * Fractions will be formatted as decimal, like '0.(3)'.
 * @param {*} value
 */
function print (value) {
  console.log(math.format(value, { fraction: 'decimal' }))
}