bigjs

A big integer library for JS, based on Leemon, with focus on prime numbers and cryptography

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Readme

BigJS
This is my big integer library, it is built on top of the big int library built by Leemon Baird.
I built it for my own interests in cryptography. It was built as Leemon's library polluted the global scope and had a somewhat scattered design. I especially love the implementations that were done for finding primes. Enjoy!

Construction

BI(number, base)

number - the actual number, this can be a string, a JS number, or another BI object base - this defaults to 10
// If you're using npm, otherwise BI is part of the window objects
var BI = require('bigjs');


var b = new BI(16772625);
//Or
var b = new BI("FFEE11", 16);
//If you put a BI object in the constructor a deep copy of that number is made
var foo = new BI(b);
//foo is now a BI object with the value 0xFFEE11

.toString(base)

base - this also defaults to 10
var b = new BI(16772625).toString(16);
//b is now the string "FFEE11"

.valueOf()

this only works by translating whatever is in the big int to a JS number. It's called whenever the object is involved in a numerical operation.
var b = (new BI(10)) * 2
//b is now 20

Constants

BI.ONE == 1
BI.ZERO == 0

Primes

prime(bits, probable)

bits - bit size of the prime, anything over 2048bits is rather slow on most machines
probable - determines whether or not this is a true prime or a probable prime. Setting this to true means that 1 in every 2^80 numbers generated may be composite. However, it has a speed up of about 10x compared to the true prime.
BI.prime(2048) //Generates a 2048 bit true prime encapsulated in the BI object

Comparisons

Operations

Arithmetic

add(num, me)

var b = new BI(1997);
b.add(19);
// Returns a new big int object with a value of 2016
b.add(19, true);
// Returns the current big int object, b, with its value changed to 2016

subtract(num, me)

var b = new BI(2016);
b.subtract(19);
// Returns a new big int object with a value of 1997
b.subtract(19, true);
// Returns the current big int object, b, with its value changed to 1997

multiply(num, me)

var b = new BI(8);
b.multiply(7);
// Returns a new big int object with a value of 56
b.multiply(7, true);
// Returns the current big int object, b, with its value changed to 56

times(num, me)

this is a synonym of .multiply()

Bitwise