HighPrecisionSquareRoot.py

# high precision square root
# Newton's method
# Juhani Kaukoranta 20.6.2018

import math
from decimal import *
def Newton(x,precision) :
    '''high precision square root'''

    getcontext().prec=precision
    x0 = Decimal(1)
    for n in range (0,70):
        x1 = (x0 + Decimal(x)/x0)/Decimal(2)
        x0 = x1
    return(x0)

a = input("Give number from which to get square root ")
x = float(a)
precision = int(input("How many digits precision, f.eq 100 "))
print("sqrt(",a,") = ",Newton(x,precision))