Function _sqrt_nearest

Lib/_pydecimal.py:5674–5687

Closest integer to the square root of the positive integer n. a is an initial approximation to the square root. Any positive integer will do for a, but the closer a is to the square root of n the faster convergence will be.

(n, a)

        return None if val_n < -e else n // 10**-e

def _sqrt_nearest(n, a):
    """Closest integer to the square root of the positive integer n.  a is
    an initial approximation to the square root.  Any positive integer
    will do for a, but the closer a is to the square root of n the
    faster convergence will be.

    """
    if n <= 0 or a <= 0:
        raise ValueError("Both arguments to _sqrt_nearest should be positive.")

    b=0
    while a != b:
        b, a = a, a--n//a>>1
    return a

def _rshift_nearest(x, shift):
    """Given an integer x and a nonnegative integer shift, return closest