## What is the standard (or best supported) big number (arbitrary precision) library for Lua?

Using lbc instead of lmapm would be easier because lbc is self-contained. local bc = require”bc” s=bc.pow(2,1000):tostring() z=0 for i=1,#s do z=z+s:byte(i)-(“0”):byte(1) end print(z)

## What is the difference between Int and Integer?

“Integer” is an arbitrary precision type: it will hold any number no matter how big, up to the limit of your machine’s memory…. This means you never have arithmetic overflows. On the other hand it also means your arithmetic is relatively slow. Lisp users may recognise the “bignum” type here. “Int” is the more common … Read more

## How to add 2 arbitrarily sized integers in C++?

Here’s an example showing how to use the OpenSSL bignum implementation for arbitrary-precision arithmetic. My example does 264 + 265. I’m using Linux. #include <cstdio> #include <openssl/crypto.h> #include <openssl/bn.h> int main(int argc, char *argv[]) { static const char num1[] = “18446744073709551616”; static const char num2[] = “36893488147419103232”; BIGNUM *bn1 = NULL; BIGNUM *bn2 = NULL; … Read more

Categories c++

## Can long integer routines benefit from SSE?

In the past, the answer to this question was a solid, “no”. But as of 2017, the situation is changing. But before I continue, time for some background terminology: Full Word Arithmetic Partial Word Arithmetic Full-Word Arithmetic: This is the standard representation where the number is stored in base 232 or 264 using an array … Read more

## Arbitrary-precision arithmetic Explanation

It’s all a matter of adequate storage and algorithms to treat numbers as smaller parts. Let’s assume you have a compiler in which an int can only be 0 through 99 and you want to handle numbers up to 999999 (we’ll only worry about positive numbers here to keep it simple). You do that by … Read more

## How to deal with big numbers in javascript [duplicate]

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) … Read more

## Working with large numbers in PHP

For some reason, there are two standard libraries in PHP handling the arbitrary length/precision numbers: BC Math and GMP. I personally prefer GMP, as it’s fresher and has richer API. Based on GMP I’ve implemented Decimal2 class for storing and processing currency amounts (like USD 100.25). A lot of mod calculations there w/o any problems. … Read more

## How to implement big int in C++

A fun challenge. 🙂 I assume that you want integers of arbitrary length. I suggest the following approach: Consider the binary nature of the datatype “int”. Think about using simple binary operations to emulate what the circuits in your CPU do when they add things. In case you are interested more in-depth, consider reading this … Read more

Categories c++

## What is the standard solution in JavaScript for handling big numbers (BigNum)?

Update(2019-08-19): BigInt is now part of Firefox and Chrome; you no longer need a library: const bigInt1 = 1111111111111111111111111111111n; const bigInt2 = BigInt(“1111111111111111111111111111111″) console.log((bigInt1 + bigInt2)+””) Original answer: If you need arbitrary-precision decimal numbers, use Javascript-bignum, as it is correct and fast.

## Fast bignum square computation

If I understand your algorithm correctly, it seems O(n^2) where n is the number of digits. Have you looked at Karatsuba Algorithm? It speeds up multiplication using the divide and conquer approach. It may be worth taking a look at.

Categories c++