Mathjs: math.chain(366.16).multiply(10).add(2).done()=3663.6000000000004

[snoopy83101]

I know js calculation is not accurate
But this is really a professional computing class library!!

professional! professional! professional!

Did not even solve!

[josdejong]

Use BigNumbers or Fractions instead of numbers

http://mathjs.org/docs/datatypes/numbers.html#roundoff-errors

[snoopy83101]

It needs to be formatted again?!
"npm install mathjs"
"import math form 'mathjs'"
"math.chain().multiply().done() "
look ,Such a perfect code!
Now you tell me, Their results are all wrong by default!
You're just kidding me

[snoopy83101]

I always thought mathjs was a perfect math class library!
JS this problem has existed for so many years
Lots and lots of scattered scripts can solve this
However, we let a default configuration output an error value

[josdejong]

WTF take it easy man. Stop talking so aggressively. Take some time to study the issue in-depth before you start screaming.

This is the famous round-off error, which is always there when doing numerical calculations with irrational numbers. There is no free lunch here, it's all about making trade-offs. It's also not a JavaScript problem, it's a generic problem when trying to represent numbers in a computer.

• Working with numbers is fast, and compatible with any other libraries that you may use. But it gives you these round-off errors.
• Working with BigNumbers is slow, but gives you less round-off errors. Less. It doesn't solve the issue, but it is much less likely to occur. You're still working with a finite number of digits so you still can't represent 1/3 correctly.
• Working with Fractions is great, but unfortunately you can't represent all irrational numbers as a Fraction.

In many use cases, working with numbers (having these round-off errors) is just fine: often performance and compatibility matters most, and the numbers may never be displayed on screen making round-off errors a non-issue, or you can easily round them to say 12 digits before displaying end-results to the user.

math.js allows you to simply configure which numeric solution suits you best, which I think is amazing. There are some ideas to make this even better and automatically convert non-BigNumber inputs to BigNumber inputs, see #864.

[firepick1]

snoopy83101, if you want to help, be nice. As it is your post is unhelpful and annoying. We are all volunteers here. How do you want to help?

[ThomasBrierley]

Maybe he can magically solve floating point precision limitations for everyone... maybe he can also invent us some gravity defying cars. Regardless there is no need for unhelpful arrogance.