"""
cube_bug.py: the same math, two ways. NumPy's ** takes a slow road
when the numbers being cubed are negative.
"""
import time
import numpy as np

def best_of(fn, reps=7):
    fn(); ts = []
    for _ in range(reps):
        t = time.perf_counter(); fn(); ts.append(time.perf_counter() - t)
    return min(ts)

rng = np.random.default_rng(0)
pos = rng.random(786_432).astype(np.float32)        # 3,072 x 256, like one floor
for name, h in [("all positive", pos), ("all negative", -pos), ("mixed (real)", pos - 0.5)]:
    a = best_of(lambda: h ** 3)
    b = best_of(lambda: h * h * h)
    print(f"{name:13s}  h**3: {a*1e3:6.2f} ms   h*h*h: {b*1e3:5.2f} ms   ({a/b:4.0f}x)")
print("numpy", np.__version__)