Square root implementations

squareroots.py

import random
import math
import numpy
import ctypes
import struct


def test_math():
    x = random.randint(0, 1000)
    root = math.sqrt(x)


def test_numpy():
    x = random.randint(0, 1000)
    root = numpy.sqrt(x)

    
def ctypes_isqrt(number):
    threehalfs = 1.5
    x2 = number * 0.5
    y = ctypes.c_float(number)

    i = ctypes.cast(ctypes.byref(y), ctypes.POINTER(ctypes.c_int32)).contents.value
    i = ctypes.c_int32(0x5f3759df - (i >> 1))
    y = ctypes.cast(ctypes.byref(i), ctypes.POINTER(ctypes.c_float)).contents.value

    y = y * (1.5 - (x2 * y * y))
    return y


def struct_isqrt(number):
    threehalfs = 1.5
    x2 = number * 0.5
    y = number

    packed_y = struct.pack('f', y)
    i = struct.unpack('i', packed_y)[0]  # treat float's bytes as int
    i = 0x5f3759df - (i >> 1)            # arithmetic with magic number
    packed_i = struct.pack('i', i)
    y = struct.unpack('f', packed_i)[0]  # treat int's bytes as float

    y = y * (threehalfs - (x2 * y * y))  # Newton's method
    return y


def numpy_isqrt(number):
    threehalfs = 1.5
    x2 = number * 0.5
    y = numpy.float32(number)

    i = y.view(numpy.int32)
    i = numpy.int32(0x5f3759df) - numpy.int32(i >> 1)
    y = i.view(numpy.float32)

    y = y * (threehalfs - (x2 * y * y))
    return float(y)


def test_numpy_fast():
    x = random.randint(0, 1000)
    root = numpy_isqrt(x)


def test_ctypes_fast():
    x = random.randint(0, 1000)
    root = ctypes_isqrt(x)


def test_struct_fast():
    x = random.randint(0, 1000)
    root = struct_isqrt(x)