frac
Rational approximation with bounded denominator
npm install frac
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Version | 0.3.1 last updated 3 months ago |
Keywords | math, fraction, rational, approximation |
Repository | git://github.com/SheetJS/frac.git (git) |
Homepage | https://github.com/SheetJS/frac |
Bugs | https://github.com/SheetJS/frac/issues |
Dependencies | None |
Dependents | maths, ssf |
frac
Rational approximation to a floating point number with bounded denominator.
Uses the Mediant Method https://en.wikipedia.org/wiki/Mediant_(mathematics)
This module also provides an implementation of the continued fraction method as described by Aberth in "A method for exact computation with rational numbers", which appears to be used by spreadsheet programs for displaying fractions
JS Installation and Usage
In node:
$ npm install frac
In the browser:
<script src="frac.js"></script>
The exported frac
function takes three arguments:
x
the number we wish to approximateD
the maximum denominatormixed
if true, return a mixed fraction (default); if false, improper
The return value is an array of the form [quot, num, den]
where quot==0
for improper fractions.
For example:
> // var frac = require('frac'); // uncomment this line if in node
> frac(Math.PI,100) // [ 0, 22, 7 ]
> frac(Math.PI,100,true) // [ 3, 1, 7 ]
frac.cont
implements the Aberth algorithm (input and output specifications
match the original frac
function)
Tests
Tests generated from Excel have 4 columns. To produce a similar test:
- Column A contains the raw values
- Column B format "Up to one digit (1/4)"
- Column C format "Up to two digits (21/25)"
- Column D format "Up to three digits (312/943)"