import numpy as np
import matplotlib.pyplot as plt

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

x = np.linspace(-0.5, 0.5, 100)
y = np.linspace(-0.5, 0.5, 100)

a, b = np.meshgrid(x, y)
c = a ** 2 + b ** 2 - 0.2

figure, axes = plt.subplots()

axes.contourf(a, b, c)

axes.set_aspect(1)

plt.show()