This question already has an answer here:
What is the standard solution in JavaScript for handling big numbers (BigNum)?
(1 answer)
Closed 7 years ago.
Is there a library available in javascript to handle large numbers with accuracy (sort of like what oracle does by storing the number as a string) and allows for operations like add/subtract/multiply/divide/mod/etc ?
Basically I need to add large numbers like 1234567890.1234567890 + 1234567890.987654321 and get a precise result.
As its author, I recommend big.js, 'a small, fast Javascript library for arbitrary-precision arithmetic with decimal numbers'.
There's a few BigInt implementations out there, for example:
JavaScript BigInteger Library
RSA In JavaScript
Layering fixed-point conversion on top of one of them should be pretty easy.
There is also a new decimal type in some implementations, based on a new definition from IEEE 754r — I believe it was part of the (now abandoned) ECMAScript 4 spec, and is carried forward by ECMAScript 3.1/5 and JavaScript 1.9, but I could be wrong on this point.
Related
I am working on open-source project. It doesn’t properly meet its specs due to the representation as JavaScript numbers ie let,const... I want to add support for Int, Long Int, and Big Ints similar to c++.
Can anyone please suggest any resource or approach to achieve this?
Thank you
JavaScript has gained BigInt support as a feature a couple of years ago. By now, most users have browsers new enough to support it: https://caniuse.com/bigint.
If you want to support even older browsers, there are a variety of pure JavaScript implementations with different pros and cons, for example JSBI, MikeMcl's bignumber.js, Peter Olson's BigInteger.js, Yaffle's BigInteger. You can study their sources to learn how they're implemented.
For learning about how native BigInt is implemented, this V8 blog post gives some insight.
Side note: JavaScript is perfectly capable of expressing 32-bit integers à la C++ int/int32_t, no BigInts or libraries are required for that. Bitwise binary operations cause JavaScript numbers to behave like 32-bit integers, so you can write (a + b) | 0 to make the addition behave like a C++ int addition.
If all you need is 64-bit integers, it's not difficult to represent them as pairs of 32-bit numbers. There are also several existing libraries that do that (just use your favorite search engine). If you don't actually need arbitrarily big integers, that may be a nice alternative.
This question already has answers here:
Is floating point math broken?
(31 answers)
Closed 2 years ago.
I'm new with JS, and i'm learning by video lectures.
In one of the video, it was said that: "
numbers are always stored in a binary format"
and this is the reason that is very hard to represent some fraction that are very easy to represent in base 10 system we are used to..
I know some development languages (c,java,etc), Is there a difference between the way that numbers are stored in JS to the way it stored in java for example?
The way numbers are stored in JS is not different to other programming languages. The fact that all numbers are stored in base 2 (aka binary) is the reason why certain fractions are hard to store in JS (and other languages). For example, the base 10 number 0.1 is 0.000110011... in binary where 0011 is recurring indefinitely. Since your computer only has a finite number if bits, you can't store 0.1 exactly, you can only approximate it, hence the unprecision.
If you need precision for numbers, most programming languages have data types to store numbers accurately. In javascript you can use the BigInteger type to store numbers more accurately. The default number type used in JS, float, however lacks the precision and runs into the issues described above.
This question already has an answer here:
What is the standard solution in JavaScript for handling big numbers (BigNum)?
(1 answer)
Closed 8 years ago.
I'm looking for a Mathematical solution that deals with really (long, big, huge, storms) numbers. I haven't found anything yet, But I don't wanna think that this problem hasn't be solve at this time. I'm looking for an easy Number solution, like Microsoft Excel Precision (30 decimals), or a BigInteger (Java) solution. in Javascript of course.
While looking for an big integer library for an ElGamal crypto implementation I tested several libraries with the following results:
I recommend this one: Tom Wu's jsbn.js (http://www-cs-students.stanford.edu/~tjw/jsbn/)
Comprehensive set of functions and fast
Leemon Baird's big integer library (http://www.leemon.com/crypto/BigInt.js)
Comprehensive set of functions and pretty fast
BUT: Negative number representation is buggy!
bignumber.js (https://github.com/MikeMcl/bignumber.js)
Pretty complete set of functions
BUT: Converting really big numbers from strings into BigNumber objects result in INFINITY
Scheme arithmetic library for JavaScript (https://github.com/jtobey/javascript-bignum)
JS-Implementation of Scheme arithmetic functions
BUT: No function for y= x^e mod n
I haven't tested this by myself: BigNumber (http://jsfromhell.com/classes/bignumber)
Functions for high precision claculations
BUT: It's said to be slow due to internal representation of numbers as strings
There's a BigInteger library for JavaScript available here:
jsbn.js
(Note that I haven't used this myself. Try it and see what you think.)
There is also Silent Matt's library for Big Integers. It does not handle decimals.
This question already has an answer here:
What is the standard solution in JavaScript for handling big numbers (BigNum)?
(1 answer)
Closed 8 years ago.
I'm looking for a Mathematical solution that deals with really (long, big, huge, storms) numbers. I haven't found anything yet, But I don't wanna think that this problem hasn't be solve at this time. I'm looking for an easy Number solution, like Microsoft Excel Precision (30 decimals), or a BigInteger (Java) solution. in Javascript of course.
While looking for an big integer library for an ElGamal crypto implementation I tested several libraries with the following results:
I recommend this one: Tom Wu's jsbn.js (http://www-cs-students.stanford.edu/~tjw/jsbn/)
Comprehensive set of functions and fast
Leemon Baird's big integer library (http://www.leemon.com/crypto/BigInt.js)
Comprehensive set of functions and pretty fast
BUT: Negative number representation is buggy!
bignumber.js (https://github.com/MikeMcl/bignumber.js)
Pretty complete set of functions
BUT: Converting really big numbers from strings into BigNumber objects result in INFINITY
Scheme arithmetic library for JavaScript (https://github.com/jtobey/javascript-bignum)
JS-Implementation of Scheme arithmetic functions
BUT: No function for y= x^e mod n
I haven't tested this by myself: BigNumber (http://jsfromhell.com/classes/bignumber)
Functions for high precision claculations
BUT: It's said to be slow due to internal representation of numbers as strings
There's a BigInteger library for JavaScript available here:
jsbn.js
(Note that I haven't used this myself. Try it and see what you think.)
There is also Silent Matt's library for Big Integers. It does not handle decimals.
This question already has answers here:
javascript large integer round because precision? (why?)
(2 answers)
Closed 8 years ago.
I've just run into a peculiar issue with Javascript.
An API call returns some JSON as it normally does. One of the ids returned is the long number "10151920335784069".
However, in Javascript world that becomes "10151920335784068" (one subtracted).
A quick test in the (Chrome) console demonstrates it:
x = 10151920335784069;
console.log(x);
10151920335784068
x==10151920335784069;
true
Further more:
x==10151920335784067;
true
x==10151920335784066;
false
What is going on here?
JavaScript (ECMA 262 5th Edition) uses double-precision 64bit numbers in IEEE 754 format. That representation cannot store your value in question exactly so it must round it to the nearest value per the IEEE 754 specification.
Authors and users of APIs that use JSON data should keep this limitation in mind. Many runtime environments (such as JavaScript) have potentially unexpected behavior regarding such numerical values even though the JSON format doesn't impose any such limitations.
All numerical variables in Javascript are stored as 64-bit floating point integers, so at high levels of precision, with numbers above 32 bits, it will round and give you slightly inaccurate numbers
If you want to check if two numbers are roughly even, you can use this
if(Math.abs(num-check)/check<1e-8)){
alert("For most practical intents and purposes, they are equal!");
}