/-where() vs. divide()

divide.py

import perfplot
import numpy as np


threshold = 0.5
# threshold = 1.0e-3

def div_where(data):
    a, b = data
    return a / np.where(b > threshold, b, 1.0)


def divide(data):
    a, b = data
    return np.divide(a, b, where=b > threshold, out=a)


b = perfplot.bench(
    setup=lambda n: np.random.rand(2, n),
    kernels=[div_where, divide],
    n_range=[2 ** k for k in range(23)],
)
b.save("out.png")
b.show()

With threshold 0.5:

With threshould 1.0e-3: