go-decimal-to-rational

Go library to convert decimal (float64) to rational fraction with required precision

Relies on Continued Fraction algorythm.

It's sometimes more appropriate than default big.Rat SetString, because you can get 2/3 from 0.6666 by specifying required precision. In big.Rat SetString you can only get 3333/50000, and have no way to manipulate than (as of go 1.11).

Example

func ExampleNewRatP() {
	fmt.Println(NewRatP(0.6666, 0.01).String())
	fmt.Println(NewRatP(0.981, 0.001).String())
	fmt.Println(NewRatP(0.75, 0.01).String())
	// Output:
	// 2/3
	// 981/1000
	// 3/4
}

func ExampleNewRatI() {
	fmt.Println(NewRatI(0.6667, 3).String())
	fmt.Println(NewRatI(0.6667, 4).String())
	// Output:
	// 2/3
	// 6667/10000
}

Docs

import dectofrac "github.com/av-elier/go-decimal-to-rational"

func NewRatI

func NewRatI(val float64, iterations int64) *big.Rat

NewRatI returns rational from decimal using iterations number of iterations in Continued Fraction algorythm

func NewRatP

func NewRatP(val float64, stepPrecision float64) *big.Rat

NewRatP returns rational from decimal by going as mush iterations, until next fraction is less than stepPrecision