tryComposite = function (a) {
    if (basic.powerMod(a, d, n) === 1) return false;

    for (var i = 0; i < s; i++) {
      if (basic.powerMod(a, Math.pow(2, i) * d, n) === n - 1) return false;
    }

    return true;
  }
Determine if a number is prime in Polynomial time, using a randomized algorithm.
http://en.wikipedia.org/wiki/Miller-Rabin_primality_test

@param {Number} number to Evaluate.
@param {Number} number to Determine accuracy rate (number of trials) default value = 20.
@return {Boolean} return true if value is prime. false otherwise.