MathUtils

a collection of math-related functions

npm install mathutils

Currently available functions

isEven(n) / isOdd(n)

Check if the bit for 2^0 is set. If it is, `n must be odd.

powermod(a, b, c)

powermod is a way of computing (a ^ b) mod c without having to deal with giant numbers that would loose their precision.

slowIsPrime(n)

Returns if n is a prime. Extremely slow, but absolutely accurate.

fastIsPrime(n)

Retuns if a n is a prime. Based upon Fermat's little theorem.

Note: Doesn't take care of carmichael primes, so you probably want to use this in combination with slowIsPrime.

isPrime(n)

Runs both fastIsPrime and slowIsPrime. This way, it manages to be both (relatively) fast and accurate.

randomPrime(length)

Returns a pseudo-random prime number (based on Math.random). length defaults to 3.

gcd(a, b)

Returns the greatest common divisor of a and b. Based on Euclids algorithm

egcd(a, b)

Computes the extended Euclidean algorithm. Returns an array [d, s, t].

gcd(a, b) = d = s * a + t * b

modularInverse(a, b)

Returns the modular multiplicative inverse of a and b.

TODO

• write tests
• add more documentation
• learn how to breakdance