Answer to Question #277743 in Python for solokin

Question

Encapsulate the following Python code from Section 7.5 in a function named my_sqrt that takes a as a parameter, chooses a starting value for x, and returns an estimate of the square root of a.

while True:

y = (x + a/x) / 2.0

if y == x:

break

x = y

Answer 1

import ​math


def my_sqrt(a):
   ​x = 1
   ​while True:
       ​y = (x + a / x) / 2.0
       ​if y == x:
           ​break
       ​x = y

   ​return y


def test_sqrt():
   ​for a in range(1000, 1020):
       ​approxsqrt = my_sqrt(a)
       ​actualsqrt = math.sqrt(a)
       ​print("a =", a,
             ​"approx. sqrt =", approxsqrt,
             ​"actual sqrt =", actualsqrt,
             ​"difference =", abs(approxsqrt - actualsqrt)