forked from jshiffer/matterbridge
55 lines
1.4 KiB
Markdown
55 lines
1.4 KiB
Markdown
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# go-decimal-to-rational
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[![Build Status](https://travis-ci.org/av-elier/go-decimal-to-rational.svg?branch=master)](https://travis-ci.org/av-elier/go-decimal-to-rational)
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Go library to convert decimal (float64) to rational fraction with required precision
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Relies on [Continued Fraction](http://mathworld.wolfram.com/ContinuedFraction.html) algorythm.
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It's sometimes more appropriate than default big.Rat SetString, because
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you can get `2/3` from `0.6666` by specifiing required precision. In big.Rat SetString
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you can only get `3333/50000`, and have no way to manipulate than (as of go 1.11).
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# Example
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```go
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func ExampleNewRatP() {
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fmt.Println(NewRatP(0.6666, 0.01).String())
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fmt.Println(NewRatP(0.981, 0.001).String())
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fmt.Println(NewRatP(0.75, 0.01).String())
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// Output:
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// 2/3
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// 981/1000
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// 3/4
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}
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```
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```go
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func ExampleNewRatI() {
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fmt.Println(NewRatI(0.6667, 3).String())
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fmt.Println(NewRatI(0.6667, 4).String())
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// Output:
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// 2/3
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// 6667/10000
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}
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```
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# Docs
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```
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import dectofrac "github.com/av-elier/go-decimal-to-rational"
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```
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#### func NewRatI
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```go
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func NewRatI(val float64, iterations int64) *big.Rat
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```
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NewRatI returns rational from decimal using `iterations` number of
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iterations in Continued Fraction algorythm
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#### func NewRatP
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```go
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func NewRatP(val float64, stepPrecision float64) *big.Rat
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```
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NewRatP returns rational from decimal by going as mush iterations, until
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next fraction is less than `stepPrecision`
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