math.simplify with Fractions

[chrisbansart]

Hi all mathjs contributors,
First of all thanks a lot for the incredible job you've achieved, math.js is really useful and impressive. I've figured out unexpected behaviour when using simplify with Fractions.
For instance:
math.simplify(math.Fraction('1/7').toString()) -> returns Object { value: 0 } => Seems to be the integer part
math.simplify(math.Fraction('9/7').toString()) -> returns Object { value: 285714 } => Seems to be the decimal part
Nevertheless
math.simplify(math.Fraction('5/4').toString()) -> returns a tree Object { implicit: false, isPercentage: false, op: "/", fn: "divide", args: (2) […] } with seems to contain the fraction.

Do you have any rational explanations ?. I use simplify with my programs that mix fractions with simplify and several times (1 out of 20 times) it occurs wrong results.
Kind regards
Chris

[josdejong]

Thanks, glad to hear you like mathjs 👍

Have a look at the output of the toString methods that you use:

console.log(math.Fraction('1/7').toString()) \\ "0.(142857)"
console.log(math.Fraction('9/7').toString()) \\ "1.(285714)"

The output (sometimes) contains a special notation to denote repeating sequences.The expression parser of mathjs doesn't support that though, and "0.(142857)" is evaluated as an implicit multiplication "0. * (142857)", and the same for "1.(285714)" which is evaluated as "1. * (285714)".

Ideally, you should be able to just pass a Fraction to simplify, but it doesn't support that (help adding that would be nice):

math.simplify(math.fraction('1/7')) 
math.simplify(math.fraction('9/7'))

What does just work though is:

math.simplify('1/7') 
math.simplify('9/7')

(though there isn't anything to simplify in those specific cases)