Show HN: libRmath.js – A port of R's Nmath numeric library to JavaScript

https://github.com/jacobbogers/libRmath.js

by Jacobot • 8 years ago

80 34 8 years ago

I am really suspect of this being actually useful for highly technical work. Why? Because I work with R, and the math that is done has very specific results that fudging floating point numbers may be a concern. I don't know enough about Javascript to be certain, but I feel like (from memory) that it does not maintain numeric accuracy at a certain level.

I am not the R nerd, my friend with the PhD is, I just do the coding around it and help clean up his brainy coding. (ie, he can code ok, so he creates the initial R code, and I clean it up so I don't go mad having to work with it) But he explained that even Excel (which I will bet is more accurate than JS) will put out inaccurate results because of number fudging at some level. (again beyond my nerd level to grok)

All of this is too bad, because R syntax is just plain rotten icky stuff. (but I may be seeing things with some of the examples looking like awful R syntax... maybe I need sleep)

Edit: Here's a comment on JS number accuracy, basically what I recalled. (this is a quick search, so take some salt with it). The issue being how JS decided to "fix" the numbers for me, felt like the magic semi colons, only not as predictable.

"In JavaScript all numbers are IEEE 754 floating point numbers.[1] Due to the binary nature of their encoding, some decimal numbers cannot be represented with perfect accuracy. This is analagous to how the fraction 1/3 cannot be accurately represented with a decimal number with a finite number of digits. Once you hit the limit of your storage you'll need to round the last digit up or down."

[0] http://adripofjavascript.com/blog/drips/avoiding-problems-wi...

[1] https://en.wikipedia.org/wiki/IEEE_754

hamandcheese• 8 years ago

JavaScript uses 64 bit floats for all numbers. Unless you deal with particularly huge integers I don’t think there will be problems.

“According to the ECMAScript standard, there is only one number type: the double-precision 64-bit binary format IEEE 754 value (numbers between -(253 -1) and 253 -1). There is no specific type for integers. In addition to being able to represent floating-point numbers, the number type has three symbolic values: +Infinity, -Infinity, and NaN (not-a-number).”

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data...

RobertRoberts8• 8 years ago

Well, the errors I ran into were happening within 4 decimal places. And the research I did at the time said you simply can't trust that the numbers will be accurate. Is this just an issue with floating point numbers in general then? This was a few years ago, maybe something has changed?

thalesmello• 8 years ago

I actually find R to have the elegant parts of List, with a more traditional language syntax. I frankly like a lot.

RobertRoberts8• 8 years ago

Well, my friend who works with R more consistently likes it ok too. Maybe it's an acquired taste. Also, he's the statistician, so perhaps it's quirky structure relates to the data in some way a laymen can't understand.

But sometimes he just wants to loop through a list and he goes a bit crazy.

bachmeier• 8 years ago

I assume you meant Lisp. R started out as a Scheme dialect, so yes, there is definitely a connection.

dbaupp3• 8 years ago

That problem is normal and expected behaviour for finite precision floating point: it appears with any scheme for floating point (IEEE-754 or not), as computers are finite. A significant chunk of the field of numerical analysis is about controlling the error introduced by floating point.

And, anyway, R uses IEEE-754 for 'numeric' too[0], and will do the same "fudging":

All R platforms are required to work with values conforming to the IEC 60559 (also known as IEEE 754) standard

There's fair criticisms that JS may not offer the required control over rounding modes that R (or the C libs underlying R) provide or the necessary instructions to minimise error accumulation, but general handwavings about "fudging" of floating point don't apply: floating point is unavoidably imprecise, and R and JS even use the same basic format.

[0] https://stat.ethz.ch/R-manual/R-devel/library/base/html/doub...

RobertRoberts8• 8 years ago

...general handwavings about "fudging" of floating point don't apply...

Handwaving is all I can do, I am just the tech taking orders.

I just talked with my statistician friend on the phone, here's one issue my friend just showed me. (integer error, not even floating point)

111,111,111 * 111,111,111 = 12,345,678,987,654,321

(I did this by hand to confirm, he made me the big meany)

Excel, Libre Office, my calculator, Javascript, etc.. all get this number wrong. But with R there's a library that can add support for numbers this big. (I guess this is a well known issue)

Edit: _All_ numbers in JS are floating point numbers, there are no integers... <hmmm>

"In JavaScript, all numbers are implemented in double-precision [...] There is no specific type for integers."

Edit 2: (for fun) This is from R:

  > library(gmp)
  > bignum <- as.bigz(111111111)
  > mul.bigz(bignum, bignum)
  Big Integer ('bigz') :
  [1] 12345678987654321

[0] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guid...

thestephen• 8 years ago

All of this is too bad, because R syntax is just plain rotten icky stuff. (but I may be seeing things with some of the examples looking like awful R syntax... maybe I need sleep)

If you can get over the way assignments are made, I find R's syntax, quite nice – especially with the pipe paradigm á tidyverse that is getting increasingly common. I personally find that the (from a software engineering perspective) awful syntax instead comes from many R users having a different background than those of other languages. I guess very few R users write unit tests, for example.

Of course, this is fine in most cases – messy, unengineered code is completely fine if few people will use it.

Jacobot7• 8 years ago

Floating point IEEE 754 is implemented in the hardware (Intel, AMD). It is a feature of the hardware not any language. We need facts not sophism.

Jacobot7• 8 years ago

The README in the github JS port has 9000 lines of documentation and code samples (R and JS side by side) to prove the output is the same for all functions.

R is fudging numbers? I dont think so, neither does JS or excel btw.

R shows limited precision to a human, you can control this with options('digits'=22) Example

options(digits=22)
1/1.2

[1] 0.83333333333333337

options(digits=4)
1/1.2

[1] 0.8333

RobertRoberts8• 8 years ago

R is fudging numbers?

I said javascript fudges numbers, not R.

williamstein• 8 years ago

I sometimes wish I had launched a similar porting effort with SageMath...

sheetjs• 8 years ago

JS can be a serious language in the data science and scientific computation fields, but one of the biggest ecosystem weaknesses is the lack of numeric libraries. This library is very promising!

johndough3• 8 years ago

Unfortunately it is impossible to implement efficient numeric libraries in JavaScript due to the lack of SIMD and GPGPU.

dagw2• 8 years ago

I assume you're talking about in the web browser/pure js? Because otherwise you can just bind to the native CUDA etc. libraries like most other languages do.

And even on the browser side SIMD is being implemented in WebAssembly and (limited) GPGPU will be possible via WebGL 2.0 compute shaders. So as such I don't see any reason why JavaScript couldn't at the very least match python/numpy in performance if someone put their mind to it.

Jacobot7• 8 years ago

Hi, I am owner of libRmath.js and porting BLAS at the moment,

Python and R cant use SIMD either (out of the box), infact no compiler can use SIMD efficiently, therefore gotoBlAS is directly written in assembler for this reason.

Secondly WebGL2 as a vast array of new texture types and Mozilla is implementing the ARB shader. But this has nothing to do with JS perse, because shader langauge is not JS, (its more C like).

mindcrash• 8 years ago

Ry disagrees:

https://github.com/propelml/propel

This is basically Tensorflow enabled to run in browser and server environments. And it does have GPGPU support via Tensorflow bindings and WebGL. Yes, really.

nickreese• 8 years ago

Perfect timing. Author if you’re reading this thanks for sharing/porting this, was just on github looking for a solution yesterday.

Jacobot7• 8 years ago

Thanks, Note, JS is breaking benchmarks if compared to Python!

pamparosendo• 8 years ago

Great work. Thanks!

Jacobot7• 8 years ago

I Want to put this here as a first level comment, some people (well actually only one) are making up stuff that JavaScript "fudges" floating point numbers.

Some ppl are going to make up drame to "sound interesting" but i dont see how that is FACTUAL.

The README contains over 8900 lines of 200+ well documented standalone code examples samples comparing JS and R code ,side by side for every function call.

THE RESULTS ARE EXACTLY THE SAME!!

Name dropping like web

Show HN: libRmath.js – A port of R's Nmath numeric library to JavaScript

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