Support ECMA 6 Draft

[AndrewGG]

There are a number of functions (e.g. hypot() and cbrt()) in the ECMA 6 Draft spec that are not currently in mathjs. These could be included in mathjs already.

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-math-object

[josdejong]

Thanks, that would be a nice addition (and not that much work to implement).

[auscompgeek]

On this note, math.js should probably also use native ES6 functions where possible.

[josdejong]

Which functions (besides hypot and cbrt)?

[auscompgeek]

Off the top of my head: hyperbolic trig functions, Math.sign, String.prototype.repeat.

[josdejong]

Ah, yes sure!

There is one thing we should be careful with: it can be the the custom built implementations have round-off errors in the 16th digit, so we have to check whether all unit tests neatly do an approximation and not an exact match of numbers.

[josdejong]

Example implementations:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/hypot https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/cbrt

https://github.com/paulmillr/es6-shim/blob/master/es6-shim.js#L1619-L1633 https://github.com/paulmillr/es6-shim/blob/master/es6-shim.js#L1564-L1577

[Yaffle]

Note: es6-shim is a little more accurate for js numbers: Math.hypot avoids underflow/overflow; Math.cbrt uses Newton's method (as you do in nth-root).

[josdejong]

Thanks, good to take that into account...

[josdejong]

I've just implemented cbrt for numbers, complex numbers, and BigNumbers. It's in the develop branch.

I will to implement hypot too.

[josdejong]

Ok then, hypot is available in develop too.

[josdejong]

Functions cbrt and hypot are available in the just released v2.3.0. Note that the website is not yet updated, but you can install the latest version via npm.

[BigFav]

As of now, we do not check for native ES6 functions where possible. I agree with @auscompgeek that we should, do you @josdejong? If so, I can go through and add Math.<function name here> || to the files.

[josdejong]

@BigFav yes sure, good idea. I suppose the native versions will be faster.

[BigFav]

@josdejong is there a clean way to type-check for a series with a mixture of types while also checking the individual types? Example, in hypot I want to isolate for a series of numbers from a series of BigNumbers or mixture of numbers and BigNumbers.

[josdejong]

That's something not yet supported by typed-function. I want to add that in the future. Well, it is supported for variable arguments like add(...number | BigNumber), but not for array like structures like say add(Array.<number | BigNumber>).

A workaround for now is to create a little helper function to typecheck individual values, like done in function median.

[BigFav]

Yeah, for this it would be pretty convenient to have something like:

'... number': Math.hypot || _hypot,
'... number | BigNumber': _hypot,

since Math.hypot would only work on a series of numbers. (This currently throws an error of conflicting types)

[josdejong]

Ah, I get your idea. That's a tricky one, as it's basically a conflicting signature. It should be possible to implement support for this in typed-function (in an efficient way) but it's not easy. Let me think about it.

[BigFav]

So I looked over the draft, and there a few functions left. I completed the ones I thought were appropriate, but I do suggest @josdejong browse the draft over.

[cshaa]

Just for completeness: as of now, math.js has implemented all Math functions except for trunc, fround, imul and clz32.

[josdejong]

Closing in favor of https://github.com/josdejong/mathjs/discussions/2692