linear congruential generator

LinearConguentialGenerator.swift

protocol RandomNumberGenerator {
    func random() -> Double
}

class LinearConguentialGenerator: RandomNumberGenerator {
    var lastRandom = 42
    let m = 139968.0
    let a = 3877.0
    let c = 29573.0

    func random() -> Double {
        lastRandom = ((lastRandom * a + c).truncatingRemainder(dividingBy:m))
        return lastRandom / m
    }
}