FediPrimes/lucas.py

# Finding lucas pseudoprimes
from math import sqrt

def isqrt(n):
    """ Find the integer square root of n via newton's method, code via
    stackoverflow:

    (https://stackoverflow.com/questions/15390807/integer-square-root-in-python)
    """
    x = n
    y = (x + 1) // 2
    while y < x:
        x = y
        y = (x + n // x) // 2
    return x

def hasIntSQRT(n):
    """Detect whether the square root of n is an integer,
    i.e. whether the isqrt(n) is the true square root.
    """
    isq = isqrt(n)
    return isq * isq == n