import math import time import random import numpy as np random.seed(time.time()) t1 = time.time() l = np.random.random((4999999)) a = np.arctan(np.cos(np.concatenate((np.power(l[l > 0.5], 1.546), np.power(l[l <= 0.5], 0.434232))) + np.arange(4999999))) t2 = time.time() print t2 - t1