Advanced Python Programming

Example 1 – checking whether a non-negative number is prime

Let's consider a quick example. Suppose that we have a simple function that checks whether a non-negative number is prime, as follows:

# Chapter08/example1.pyfrom math import sqrtdef is_prime(x):    if x < 2:    return Falseif x == 2:    return Trueif x % 2 == 0:    return Falselimit = int(sqrt(x)) + 1    for i in range(3, limit, 2):        if x % i == 0:            return Falsereturn True

Also, suppose that we have a list of significantly large integers (10¹³ to 10¹³ + 500), and we want to check whether each of them is prime by using the preceding function:

input = [i for i in range(10 ** 13, 10 ** 13 + 500)]

A sequential approach would be to simply pass one number after another to the is_prime() function, as follows: ...