bigint

Arbitrary precision integral arithmetic for node.js!

This library wraps around libgmp's integer functions to perform infinite-precision arithmetic.

You should also consider using bignum, which is based on the bigint api but uses openssl instead of libgmp, which you are more likely to already have on your system.

example

simple.js

var bigint = require('bigint');

var b = bigint('782910138827292261791972728324982')
    .sub('182373273283402171237474774728373')
    .div(8)
;
console.log(b);

---

$ node simple.js
<BigInt 75067108192986261319312244199576>

perfect.js

Generate the perfect numbers:

// If 2**n-1 is prime, then (2**n-1) * 2**(n-1) is perfect.
var bigint = require('bigint');

for (var n = 0; n < 100; n++) {
    var p = bigint.pow(2, n).sub(1);
    if (p.probPrime(50)) {
        var perfect = p.mul(bigint.pow(2, n - 1));
        console.log(perfect.toString());
    }
}

---

6
28
496
8128
33550336
8589869056
137438691328
2305843008139952128
2658455991569831744654692615953842176
191561942608236107294793378084303638130997321548169216

methods[0]

bigint(n, base=10)

Create a new bigint from n and a base. n can be a string, integer, or another bigint.

If you pass in a string you can set the base that string is encoded in.

.toString(base=10)

Print out the bigint instance in the requested base as a string.

bigint.fromBuffer(buf, opts)

Create a new bigint from a Buffer.

The default options are: { order : 'forward', // low-to-high indexed word ordering endian : 'big', size : 1, // number of bytes in each word }

Note that endian doesn't matter when size = 1.

methods[1]

For all of the instance methods below you can write either

bigint.method(x, y, z)

or if x is a bigint instance``

x.method(y, z)

.toNumber()

Turn a bigint into a Number. If the bigint is too big you'll lose precision or you'll get ±Infinity.

.toBuffer(opts)

Return a new Buffer with the data from the bigint.

The default options are: { order : 'forward', // low-to-high indexed word ordering endian : 'big', size : 1, // number of bytes in each word }

Note that endian doesn't matter when size = 1.

.add(n)

Return a new bigint containing the instance value plus n.

.sub(n)

Return a new bigint containing the instance value minus n.

.mul(n)

Return a new bigint containing the instance value multiplied by n.

.div(n)

Return a new bigint containing the instance value integrally divided by n.

.abs()

Return a new bigint with the absolute value of the instance.

.neg()

Return a new bigint with the negative of the instance value.

.cmp(n)

Compare the instance value to n. Return a positive integer if > n, a negative integer if < n, and 0 if == n.

.gt(n)

Return a boolean: whether the instance value is greater than n (> n).

.ge(n)

Return a boolean: whether the instance value is greater than or equal to n (>= n).

.eq(n)

Return a boolean: whether the instance value is equal to n (== n).

.lt(n)

Return a boolean: whether the instance value is less than n (< n).

.le(n)

Return a boolean: whether the instance value is less than or equal to n (<= n).

.and(n)

Return a new bigint with the instance value bitwise AND (&)-ed with n.

.or(n)

Return a new bigint with the instance value bitwise inclusive-OR (|)-ed with n.

.xor(n)

Return a new bigint with the instance value bitwise exclusive-OR (^)-ed with n.

.mod(n)

Return a new bigint with the instance value modulo n.

m. .pow(n)

Return a new bigint with the instance value raised to the nth power.

.powm(n, m)

Return a new bigint with the instance value raised to the nth power modulo m.

.invertm(m)

Compute the multiplicative inverse modulo m.

.rand()

.rand(upperBound)

If upperBound is supplied, return a random bigint between the instance value and upperBound - 1, inclusive.

Otherwise, return a random bigint between 0 and the instance value - 1, inclusive.

.probPrime()

Return whether the bigint is:

• certainly prime (true)
• probably prime ('maybe')
• certainly composite (false)

using mpz_probab_prime.

.nextPrime()

Return the next prime greater than this using mpz_nextprime.

.sqrt()

Return a new bigint that is the square root. This truncates.

.root(n)

Return a new bigint that is the nth root. This truncates.

.shiftLeft(n)

Return a new bigint that is the 2^n multiple. Equivalent of the << operator.

.shiftRight(n)

Return a new bigint of the value integer divided by 2^n. Equivalent of the >> operator.

.gcd(n)

Return the greatest common divisor of the current bigint with n as a new bigint.

.bitLength()

Return the number of bits used to represent the current bigint as a javascript Number.

install

You'll need the libgmp source to compile this package. Under Debian-based systems,

sudo aptitude install libgmp3-dev

On a Mac with Homebrew,

brew install gmp

And then install with npm:

npm install bigint